#include<iostream>
#include<iomanip>
#include<cmath>
#include<cstdio>
#include<string>
#include<algorithm>
#include<cstdlib>
#include<queue>
#include<stack>
#include<vector>
#include<new>
#include<random>
using namespace std;
int main() {
    int a, b, ans = -1;
    scanf("%d%d", &a, &b);
    if (900 + a % 100 - b > a - 100 - b % 100)
        ans = (900 + a % 100 - b);
    if (a - 100 - b % 100 > 900 + a % 100 - b)
        ans = (a - 100 - b % 100);
    if (90 + a / 100 * 100 + a % 10 - b > a - b / 100 * 100 - b % 10)
        if (ans < 90 + a / 100 * 100 + a % 10 - b)
            ans = (90 + a / 100 * 100 + a % 10 - b);
    if (a - b / 100 * 100 - b % 10 > 90 + a / 100 * 100 + a % 10 - b)
        if (ans < a - b / 100 * 100 - b % 10)
            ans = (a - b / 100 * 100 - b % 10);
    if (9 + a / 10 * 10 - b > a - b / 10 * 10)
        if (ans < 9 + a / 10 * 10 - b)
            ans = (9 + a / 10 * 10 - b);
    if (a - b / 10 * 10 > 9 + a / 10 * 10 - b)
        if (ans < a - b / 10 * 10)
            ans = (a - b / 10 * 10);
    else
        ans = a - b;
    printf("%d", ans);
}