#include <iostream>
#include <conio.h>
using namespace std;
char *operation(char *&mass_1, char *&mass_2, char oper);
void Invert(char *&mass);
char *Plus(char *&mass_1, char *&mass_2);
char *Minus(char *&mass_1, char *&mass_2);


char *operation(char *&mass_1, char *&mass_2, char oper) {
	char simbol_1 = mass_1[0];
	char simbol_2 = mass_2[0];

	Invert(mass_1);
	Invert(mass_2);

	char *result;
	bool minus = 0;

	if (simbol_1 == '-') {
		if (simbol_2 == '-') {
			if (oper == '-')
			{
				result = Minus(mass_2, mass_1);
			}
			else
			{
				result = Plus(mass_1, mass_2);
				minus = 1;
			}
		}
		else {
			if (oper == '-') {
				result = Plus(mass_2, mass_1);
				minus = 1;
			}
			else {
				result = Minus(mass_2, mass_1);
			}
		}
	}
	else {
		if (simbol_2 == '-') {
			if (oper == '-') {
				result = Plus(mass_2, mass_1);
			}
			else {
				result = Minus(mass_1, mass_2);
			}
		}
		else {
			if (oper == '-') {
				result = Minus(mass_1, mass_2);
			}
			else {
				result = Plus(mass_2, mass_1);
			}
		}
	}

	if (minus) {
		int i = 1;
		for (; result[i]; i++) {
		}
		for (i--; i >= 0; i--) {
			result[i + 1] = result[i];
		}

		result[0] = '-';
	}

	return result;
}
char *Plus(char *&mass_1, char *&mass_2) {
	char *result = new char[10];
	short ind_1 = 1, ind_2 = 1;
	for (; mass_1[ind_1]; ind_1++) {

	}
	for (; mass_2[ind_2]; ind_2++) {

	}

	if (ind_2 > ind_1) {
		for (int i = ind_1; i != ind_2; i++) {
			mass_1[i] = '0';
		}
		for (short delta = ind_2 - ind_1, i = ind_1 - 1; i >= 0; i--) {
			mass_1[i + delta] = mass_1[i];
			mass_1[i] = '0';
		}
		ind_1 = ind_2;
	}
	if (ind_1 > ind_2) {
		for (int i = ind_2; i != ind_1; i++) {
			mass_2[i] = '0';
		}
		for (short delta = ind_1 - ind_2, i = ind_2 - 1; i >= 0; i--) {
			mass_2[i + delta] = mass_2[i];
			mass_2[i] = '0';
		}
	}



	int k = 0;
	for (int i = ind_1 - 1; i >= 0; i--) {
		result[i] = mass_1[i] + mass_2[i] - '0' + k;
		if (result[i] > 'A' - 6) {
			k = 1;
			result[i] = result[i] - 11;
		}
		else k = 0;
	}

	if (k) {
		for (int i = ind_1 - 1; i >= 0; i--) {
			result[i + 1] = result[i];
		}
		result[0] = '1';
	}

	return result;
}
char *Minus(char *&mass_1, char *&mass_2) {
	char *result = new char[10];
	short ind_1 = 1, ind_2 = 1;
	for (; mass_1[ind_1]; ind_1++) {

	}

	for (; mass_2[ind_2]; ind_2++) {

	}

	if (ind_2 > ind_1) {
		for (int i = ind_1; i != ind_2; i++) {
			mass_1[i] = '0';
		}
		for (short delta = ind_2 - ind_1, i = ind_1 - 1; i >= 0; i--) {
			mass_1[i + delta] = mass_1[i];
			mass_1[i] = '0';
		}
		ind_1 = ind_2;
	}
	if (ind_1 > ind_2) {
		for (int i = ind_2; i != ind_1; i++) {
			mass_2[i] = '0';
		}
		for (short delta = ind_1 - ind_2, i = ind_2 - 1; i >= 0; i--) {
			mass_2[i + delta] = mass_2[i];
			mass_2[i] = '0';
		}
	}

	bool normal = 1;
	for (int i = 0; mass_1[i]; i++) {
		if (mass_1[i] != mass_2[i]) {
			if (mass_1[i] < mass_2[i]) {
				normal = 0;
			}
			break;
		}
	}



	if (normal) {
		int k = 0;
		for (int i = ind_1 - 1; i >= 0; i--) {
			result[i] = mass_1[i] - mass_2[i] + '0' - k;
			if (result[i] < '0') {
				k = 1;
				result[i] = result[i] + 12;
			}
			else k = 0;
		}
	}
	else {
		int k = 0;
		for (int i = ind_1 - 1; i >= 0; i--) {
			result[i + 1] = mass_2[i] - mass_1[i] + '0' - k;
			if (result[i + 1] < '0') {
				k = 1;
				result[i + 1] = result[i + 1] + 12;
			}
			else k = 0;
		}
		result[0] = '-';
	}



	return result;
}
void Invert(char *&mass) {
	if (mass[0] == '-') {
		short i;
		for (i = 1; mass[i]; i++) {
			mass[i - 1] = mass[i];
		}
		mass[i - 1] = '\0';
	}
}

int main()
{
	setlocale(LC_ALL, "Rus");
	char *mass_1 = new char[9];
	char *mass_2 = new char[9];
	char oper;
	cout << "Input the operation" << endl;
	cin >> mass_1; cin >> oper; cin >> mass_2;
	cout << mass_1 << " " << oper << " " << mass_2 << " = ";

	for (short i = 0; mass_1[i]; i++) {
		if (mass_1[i] > '9' && mass_1[i] < 'C') {
			mass_1[i] -= 7;
		}
	}
	for (short i = 0; mass_2[i]; i++) {
		if (mass_2[i] > '9' && mass_2[i] < 'C') {
			mass_2[i] -= 7;
		}
	}

	char *result = operation(mass_1, mass_2, oper);

	for (short i = 0; result[i]; i++) {
		if (result[i] > '9' && result[i] < 'C' - 7) {
			result[i] += 7;
		}
	}


	cout << result;

	system("pause");

	delete[] result;
	delete[] mass_1;
	delete[] mass_2;

}