#include<bits/stdc++.h>
using namespace std;
const int N=1e5+10;
int a[N],b[N];
int n;
void jian(int a[],int b[])
{
    for(int i=0,t=0;i<n;i++)
    {
        a[i]=a[i]-b[i]-t;
        if(a[i]<0)a[i]+=10,t=1;
        else t=0;
    }
}
bool check(string A,string B)
{
    if(A.size()!=B.size())return A.size()>B.size();
    else return A>=B;
}
int main()
{
    string A,B;
    cin>>A>>B;
    if(!check(A,B))
    {
        cout<<'-';
        swap(A,B);
    }
    for(int i=A.size()-1;i>=0;i--)
    a[i]=A[A.size()-1-i]-'0';
    n=A.size();
    for(int i=B.size()-1;i>=0;i--)
    b[i]=B[B.size()-1-i]-'0';
    jian(a,b);
    int cnt=A.size()-1;
    while(a[cnt]==0&&cnt!=0)cnt--;
    for(int i=cnt;i>=0;i--)cout<<a[i];
    return 0;
}