#include<iostream>
#include<vector>
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;
    int t=0;
    for(int i=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;             //11111111111111111111111111
        else t=0;
    }
    while(C.size()>1&&C.back()==0) C.pop_back();
    return C;
}
int main(){
    string a,b;
    vector<int>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');
    vector<int>C;
    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];
    cout<<endl;
    return 0;

}