#include<bits/stdc++.h>
using namespace std;

string a, b;
vector<int> A, B;

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, 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(){
    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)){
        auto C = sub(A, B);
        for(int i = C.size() - 1; i >= 0; -- i) cout << C[i];
    }
    else{
        auto C = sub(B, A);
        cout << '-';
        for(int i = C.size() - 1; i >= 0; -- i) cout << C[i];
    }



}