#include<iostream>
#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;
    cin>>a>>b;
    vector<int>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))
    {
        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;
}