$\texttt{rt}$

code:

#include <iostream>
#include <string>
using namespace std;

int ia[10100], ib[10100];

int main()
{
	string a, b;
	cin >> a >> b;
	if(a.size() < b.size())
	{
		cout << "-";
		string c;
		c = a;
		a = b;
		b = c;
	}
	else if(a.size() == b.size())
	{
		for(int i = 0; i <= a.size() - 1; i ++)
		{
			if(a[i] < b[i])
			{
				cout << "-";
				string c;
				c = a;
				a = b;
				b = c;
				break;
			}
		}
	}
	if(a.size() > b.size())
	{
		int sz = (a.size() - b.size());
		for(int i = 1; i <= sz; i++)
		{
			b = "0" + b;
			cout << b << " "  << i << endl;
		}
	}
	for(int i = 1; i <= a.size(); i++)
	{
		ia[i] = a[i - 1] - '0';
		cout << ia[i];
	}
	cout << endl;
	for(int i = 1; i <= b.size(); i++)
	{
		ib[i] = b[i - 1] - '0';
		cout << ib[i];
	}
	cout << endl;
	for(int i = a.size(); i >= 1; i--)
	{
		ia[i] = ia[i] - ib[i];
		if(ia[i] < 0)
		{
			ia[i - 1]--;
			ia[i] += 10;
		}
	}
	int i = 1;
	while(ia[i] == 0)
	{
		i++;
	}
	for(; i <= a.size(); i++)
	{
		cout << ia[i];
	}
	return 0;
}