#include<bits/stdc++.h>
using namespace std;
string n,m;
int a[100000],b[100000],c[100000];
int main(){
	cin>>n>>m;
	int lenn=n.length();
	int lenm=m.length();
	if(lenn<lenm ||(lenn==lenm && n<m )){
		cout<<"-";
		string x;
		x=n;
		n=m;
		m=x;
		int x1;
		x1=lenn;
		lenn=lenm;
		lenm=x1;
	}
	for (int i=0;i<lenn;i++)
		a[i]=n[lenn-i-1]-'0';
	for (int i=0;i<lenm;i++)
		b[i]=m[lenm-i-1]-'0';
	int i=0;
	while (i<lenm||i<lenn){
		if (a[i]<b[i]){
			a[i]+=10;
			a[i+1]--;
		}
		c[i]=a[i]-b[i];
		i++;
	}
	int lenc=i;
	if (c[lenc]==0)lenc--;
	for (int i=lenc;i>-1;i--)
		cout<<c[i];
	return 0;
}