#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
const int N=3e2;
int a[N],b[N],c[N];
int main(){
	string aa,bb;
	cin >>aa >> bb;
	int lena=aa.size();
	int lenb=bb.size();
	if(lena<lenb || (lena==lenb&&aa<bb))
	{
		cout << "-";
		swap(lena,lenb);
		swap(aa,bb);
	}
	for(int i = 0; i < lena; i++)
	{
		a[i]=aa[lena-1-i]-'0';
	}
	for(int i = 0; i < lenb; i++)
	{
		b[i]=bb[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];
	}
}