#include<bits/stdc++.h>
using namespace std;
int a[100100];
int b[100100];
int c[100100];
int main(){
	string s1,s2;
	cin>>s1>>s2;
	if(s1.size()<s2.size()||(s1.size()==s2.size()&&s1<s2)){
		swap(s1,s2);
		cout<<"-";
	}
	long long len1=s1.size();
	long long len2=s2.size();
	for(int i=len1-1;i>=0;i--){
		a[i]=s1[len1-1-i]-'0';
	}
	for(int i=len2-1;i>=0;i--){
		b[i]=s2[len2-1-i]-'0';
	}
	long long len3=max(len1,len2);
	for(int i=0;i<len1;i++){
		if(a[i]<b[i]){
			a[i]+=10;
			a[i+1]-=1;
			c[i]=a[i]-b[i];
		}else{
			c[i]=a[i]-b[i];
		}
	}
	while(c[len3-1]==0&&len3>1){
		len3--;
	}
	for(int i=len3-1;i>=0;i--){
		cout<<c[i];
	}
	return 0;
}