#include <iostream>
#include <vector>
using namespace std;
const int N=1000010;
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;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.back()==0&&C.size()>1)C.pop_back();
 for(int i=C.size()-1;i>=0;i--)
 if(C.back()!=0)break;
 else if(!C.back())C.pop_back();
 if(C.size()==0)C.push_back(0);
    return C;
}

int main()
{
    string a,b;
    cin>>a>>b;
    vector<int>A,B,C;
    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))C=sub(A,B);
    else {
        C = sub(B, A);
        cout<<'-';
    }
    for (int i=C.size()-1;i>=0;i--) cout<<C[i];
    return 0;
}