#include <iostream>
#include <algorithm>

using namespace std;

bool cmp(vector<int> &A, vector<int> &B)
{
    // A >= 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; //所有的都相等
}

vector<int> sub(vector<int> &A, vector<int> &B)
{
    int t = 0;
    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();  //去掉前导零

    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--) printf("%d", C[i]);


    return 0;
}