//
// Created by wangliewei on 2021/8/12.
//
#include<iostream>
#include<vector>
using namespace std;

//判断是否有 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;
    for (int i = 0, t = 0; i < A.size(); i++){
        t = A[i] - t;
        //因为此时B的size一定比A小，所以这里要做一个判断，如果B[i]还有，再减去它
        if (i < B.size()) t = t - B[i];
        C.push_back((t + 10) % 10);//综合两种情况，即t>=0，还是t本身；和t<0.应该是t + 10
        //判断是否需要借位
        if(t < 0) t = 1;
        else t = 0;
    }

    //比如123-120,答案是003，那么要去掉前面的0;但是比如9-9，答案是0，有不能去掉，所以C.size要大于1
    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');

    if(cmp(A, B)){
        auto C = sub(A, B);
        for (int i = C.size()-1; i >= 0; i--) printf("%d", C[i]);
    } else{
        auto C = sub(B, A);
        printf("-");
        for (int i = C.size()-1; i >= 0; i--) printf("%d", C[i]);
    }
    return 0;
}