#include <bits/stdc++.h>//114514廖浩宇 
using namespace std;
const int N = 1e5 + 1;
int a[N],b[N],c[N];
int main()
{
	string a1,b1;
	cin >> a1 >> b1;
	int lena = a1.size();
	int lenb = b1.size();
	if(lena < lenb || (lena == lenb && a1 < b1))
	{
		cout << "-";
		swap(lena,lenb);
		swap(a1,b1);
	}
	for(int i = 0; i < lena; i++)
		a[i] = a1[lena - 1 - i] - '0';
	for(int i = 0; i < lenb; i++)
		b[i] = b1[lenb - 1 - i] - '0';
	for(int i = 0; i < lena; i++)
	{
		c[i] += a[i] - b[i];
		if(c[i] < 0)
		{
			c[i] += 10;
			a[i + 1] -= 1;
		}
	}
	while(c[lena] == 0 && lena > 0)
		lena--;
	for(int i = lena; i >= 0; i--)
		cout << c[i];
}