#include<bits/stdc++.h>
using namespace std;
string s1,s2;
int a[245],b[245],c[245]; 
int main(){
    cin>>s1>>s2; 
    if(s2.size()>s1.size()||(s2.size()==s1.size()&&s1<s2)){
        cout<<"-";
        swap(s1,s2);
    }
    for(int i=0;i<=s1.size()-1;i++){
		 a[i]=s1[s1.size()-1-i]-'0';}
    for(int i=0;i<=s2.size()-1;i++){
		 b[i]=s2[s2.size()-1-i]-'0';}
    int len=s1.size();
    for(int i=0;i<=len-1;i++){
        if(a[i]<d[i]){
            a[i+1]=a[i+1]-1;
            a[i]=a[i]+10;
        }
        c[i]=a[i]-b[i];
    } 
    int p=0; 
    for(int i=len-1;i>=0;i--){
        if(e[i]!=0){
            p=i;
            break;
        }   
    }
    for(int i=p;i>=0;i--){
		cout<<c[i];}
    return 0;
}
/**************************************************************
	Problem: 1269
	User: panyuchen
	Language: C++
	Result: Compile Error
****************************************************************/