#include <iostream>
#include <string>

#define N 10

using namespace std;

struct Number {
    int* num;
    Number() {
        num = new int[N];
    }

};

void output(Number a) {
    int i = 0;

    while (i < N && a.num[i] == 0)
        i++;

    if (i == N)
        cout << "0";

    for (i; i < N; i++) {
        cout << a.num[i];
    }

    cout << endl;
}

Number init(Number a) {

    for (int i = 0; i < N; i++)
        a.num[i] = 0;

    return a;
}

Number enter(Number a, Number b) {
    string str;
    int length;
    Number num = init();

    cout << "Enter the number:" << endl;
    cin >> str;

    length = str.length();

    for (int i = 0; i < str.length(); i++) {
        num.num[N - str.length() + i] = str[i] - '0';
    }


    return num;
}
Number sum(Number a, Number b) {

    Number c = init();

    for (int i = N - 1; i > 0; i--) {
        c.num[i] = a.num[i] + b.num[i];

        if (c.num[i] > 9) {
            c.num[i] = c.num[i] - 10;
            c.num[i - 1] = 1;
        }
    }

    output(c);
}


int compare(Number a, Number b) {

    for (int i = 0; i < N; i++) {
        if (a.num[i] > b.num[i]) {
            return 1;
        }
        else if (a.num[i] < b.num[i]) {
            return -1;
        }
    }

    return 0;
}

Number minus(Number a, Number b) {

    Number c = init();

    for (int i = N - 1; i > 0; i--) {
        c.num[i] += a.num[i] - b.num[i];

        if (c.num[i] < 0) {
            c.num[i] += 10;
            c.num[i - 1] = -1;
        }
    }

    output(c);
}

int main() {
    int i, j;
    Number* a = new Number[N];
    Number* b = new Number[N];
    Number* c = new Number[N];
   Number a;

    a = enter();
    cout << endl;

    b = enter();
    cout << endl;

    int comp = compare(a, b);

    if (comp == 1) {
        cout << "a > b" << endl;
    }
    else if (comp == 0) {
        cout << "a == b" << endl;
    }
    else if (comp == -1) {
        cout << "a < b" << endl;
    }

    cout << endl << "The sum = ";

    c = sum(a, b);

    output(c);

    cout << endl << "The subtraction is = ";

    if (comp != -1) {
        c = minus(a, b);
    }
    else {
        cout << "-";
        c = minus(b, a);
    }

    delete[]c;

    cout << endl;


    system("pause");

    return 0;
}