#include <iostream>
#include <string>
using namespace std;

int main() 
{
    int A, B;
    cin>>A>>B;

    int correct = A-B;
    string s = to_string(correct);

    int n = s.size();

    if (s[n-1]!='9') 
    {
        s[n-1] = s[n-1]+1;
    } 
    else 
    {
        s[n-1] = s[n-1]-1;
    }
    cout<<s;
    return 0;
}