Ошибка Thread 1: EXC_BAD_ACCESS (code=1, address=0x0) при компиляции

Необходимо написать класс для работы с целыми знаковыми числами с использованием stl и виртуальных функций.(С++03). Ошибка в строке 235 ''CIntN tmp = -((dynamic_cast(arr[0])))''

#include <algorithm>
#include <iostream>
#include <iterator>
#include <fstream>
#include <sstream>
#include <vector>
class CIntN {
protected:
    std::string filename;
    std::vector<int> nums;
    class Adder {
        int carry;
    public:
        Adder(): carry(0) {}
        int operator()(int x, int y) {
            int oldcarry = carry;
            carry = (x + y + oldcarry) / 10;
            return (x + y + oldcarry) % 10;
        }
    };
    class Invertor {
    public:
        int operator()(int x) {
            return 9 - x;
        }
    };
public:
    virtual int output(const char* FileName = NULL) = 0;
    virtual CIntN& with(const char* str = NULL);
    virtual CIntN& operator=(const CIntN&);
    virtual CIntN* operator-() const = 0;
    virtual CIntN& operator+=(const CIntN&);
    virtual CIntN& operator-=(const CIntN&);
    virtual CIntN& negate();
    virtual ~CIntN() {
    };
};
CIntN& CIntN::with(const char *str) {
    std::stringstream ss((std::string(str)));
    int num;
    ss >> num;
    ss >> filename;
    int n;
    ss >> n;
    nums = std::vector<int>(n + 1, 0);
    std::string number;
    ss >> number;
    std::string::reverse_iterator end = number.rend();
    std::vector<int>::reverse_iterator vit = nums.rbegin();
    if (number[0] == '-' || number[0] == '+') --end;
    for (std::string::reverse_iterator it = number.rbegin(); it != end
         && vit != nums.rend(); ++it, ++vit) {
        *vit = *it - '0';
    }
    if (number[0] == '-') {
        negate();
    }
    return *this;
}
CIntN& CIntN::negate() {
    std::transform(nums.begin(), nums.end(), nums.begin(), Invertor());
    int carry = (*(nums.rbegin()) + 1) / 10;
    *(nums.rbegin()) = (*(nums.rbegin()) + 1) % 10;
    std::vector<int>::reverse_iterator it = nums.rbegin() + 1;
    for (; it < nums.rend(); ++it) {
        int oldcarry = carry;
        carry = (*it + oldcarry) / 10;
        *it = (*it + oldcarry) % 10;
    }
    return *this;
}
CIntN& CIntN::operator=(const CIntN& other) {
    nums.clear();
    std::copy(other.nums.begin(), other.nums.end(), std::back_inserter(nums));
    return *this;
}
CIntN& CIntN::operator+=(const CIntN& other) {
    if (nums.size() != other.nums.size()) {
        std::cerr << "Attempt to add CIntN's with different sizes!" << std::endl;
    }
    std::transform(nums.rbegin(), nums.rend(), other.nums.rbegin(), nums.rbegin(), Adder());
    return *this;
}
CIntN& CIntN::operator-=(const CIntN& other) {
    CIntN *tmp = -other;
    *this += *tmp;
    delete tmp;
    return *this;
}
class CIntN0: public CIntN {
public:
    CIntN0() {
        nums = std::vector<int>();
    }
    CIntN0(const CIntN0& n0) {
        nums = std::vector<int>(n0.nums);
    }
    int output(const char* FileName = NULL) {
        std::ofstream of;
        if (FileName) {
            of.open(FileName);
        } else {
            of.open(filename.c_str());
        }
        of << nums.size() - 1 << " ";
        std::vector<int>::iterator it = nums.begin();
        if (nums[0] >= 5) {
            of << '-';
            negate();
        }
        while (*it == 0 && it != nums.end()) ++it;
        if (it == nums.end()) {
            of << 0;
        } else {
            std::copy(it, nums.end(), std::ostream_iterator<int>(of, ""));
        }
        of << std::endl;
        of.close();
        return 0;
    }
    CIntN* operator-() const {
        CIntN0 *ci = new CIntN0(*this);
        ci->negate();
        return ci;
    }
    ~CIntN0() {
    }
};
CIntN0 operator+(const CIntN0 &first, const CIntN0 &second) {
    CIntN0 res(first);
    res += second;
    return res;
}
CIntN0 operator-(const CIntN0 &first, const CIntN0 &second) {
    CIntN0 res(first);
    res -= second;
    return res;
}
class CIntN1: public CIntN {
public:
    CIntN1() {
        nums = std::vector<int>();
    }
    CIntN1(const CIntN1& n1) {
        nums = std::vector<int>(n1.nums);
    }
    int output(const char* FileName = NULL) {
        std::ofstream of;
        if (FileName) {
            of.open(FileName);
        } else {
            of.open(filename.c_str());
        }
        of << nums.size() - 1 << std::endl;
        std::vector<int>::iterator it = nums.begin();
        if (nums[0] >= 5) {
            of << '-';
            negate();
        }
        while (*it == 0 && it != nums.end()) ++it;
        if (it == nums.end()) {
            of << 0;
        } else {
            std::copy(it, nums.end(), std::ostream_iterator<int>(of, ""));
        }
        of << std::endl;
        of.close();
        return 0;
    }
    CIntN* operator-() const {
        CIntN1 *ci = new CIntN1(*this);
        ci->negate();
        return ci;
    }
    ~CIntN1() {
    }
};
CIntN1 operator+(const CIntN1 &first, const CIntN1 &second) {
    CIntN1 res(first);
    res += second;
    return res;
}
CIntN1 operator-(const CIntN1 &first, const CIntN1 &second) {
    CIntN1 res(first);
    res -= second;
    return res;
}
class CIntNFactory {
    int i;
public:
    CIntNFactory(int i): i(i) {};
    CIntN *createCIntN(const char* str);
    ~CIntNFactory() {
    }
};
CIntN *CIntNFactory::createCIntN(const char *str) {
    CIntN *ci;
    if (i == 0) {
        ci = new CIntN0();
    } else if (i == 1) {
        ci = new CIntN1();
    } else return NULL;
    ci->with(str);
    return ci;
}
CIntN *CreateCIntN(const char *str, CIntNFactory** factories) {
    return factories[str[0] - '0']->createCIntN(str);
}
int main() {
    std::string str;
    CIntNFactory **factories = new CIntNFactory*[2];
    factories[0] = new CIntNFactory(0);
    factories[1] = new CIntNFactory(1);
    std::ifstream in("input.txt");
    std::vector<CIntN*> arr;
    while (std::getline(in, str)) {
        arr.push_back(CreateCIntN(str.c_str(), factories));
    }
    CIntN *tmp = -(*(dynamic_cast<CIntN0*>(arr[0])));
    tmp->output("output6.txt");
    delete tmp;
    (*(dynamic_cast<CIntN1*>(arr[1])) + *(dynamic_cast<CIntN1*>(arr[3]))).output("output5.txt");
    for (std::vector<CIntN*>::iterator it = arr.begin(); it != arr.end(); ++it) {
        (*it)->output();
        delete *it;
    }
    delete factories[0];
    delete factories[1];
    delete[] factories;
    return 0;
}