#include <iostream>
#include <cstring>
#include <algorithm>
#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;
    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()
{
    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];
    return 0;
}