#include<bits/stdc++.h>
using namespace std;
bool cmp(vector<int>&A,vector<int>&B) {
if(A.size()!=B.size())
return A.size()>B.size();
for(int i=A.size()-1;i>=0;i--){
    if(A[i]!=B[i])return A[i]>B[i];
}   
return true;
}
vector<int>sub(vector <int>&A,vector<int>&B){

    vector<int>c;
    for(int i=0,t=0;i<A.size();i++){
        t=A[i]-t;
        if(i<B.size())t-=B[i];

        c.push_back((t+10)%10);
        if(t<0)t=1;
        else t=0;
    } 
    while(c.size()>1&&c.back()==0)c.pop_back();

    return c;
}
int main(){
    vector<int>A,B,c;
    string a,b;
    cin>>a>>b;
    for(int i=a.size()-1;i>=0;i--)A.push_back(a[i]-'0');
    for(int i=b.size()-1;i>=0;i--)B.push_back(b[i]-'0');
    if(cmp(A,B)){
        c=sub(A,B);
    }else{
        c=sub(B,A);
        cout<<"-";
    }
        for(int  i=c.size()-1;i>=0;i--){
            cout<<c[i];
        }
    return 0;
}