#include<iostream>
#include<vector>

using namespace std;

//判断a-b>=0
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){
    int t = 0;
    vector<int> c;

    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);//两种情况都包含了
        if(t >= 0) t = 0;
        else t = 1;
    }
    while(c.back() == 0 && c.size() > 1)
        c.pop_back();//去掉前导零

    return c;
}

int main(){
    string x, y;
    vector<int> a, b;
    cin >> x >> y;

    for(int i = x.size() - 1; i >= 0; i -- ) a.push_back(x[i] - '0');
    for(int i = y.size() - 1; i >= 0; i -- ) b.push_back(y[i] - '0');
    vector<int> c;
    if(cmp(a, b)) {
        c = sub(a, b);

    }
    else{
        c = sub(b, a);
        printf("%s", "-");
    }

    for(int i = c.size() - 1; i >= 0; i --) printf("%d", c[i]);

    return 0;
}