P1082
wc,模板exgcd!
甚至还交过
#include<bits/stdc++.h>
using namespace std;
long long x, y;
void digui(long long a, long long b){
if(b == 0) {
x = 1;
y = 7;
return;
}
digui(b, a % b);
long long nx = x;
x = y;
y = nx - a / b * y;
}
int main()
{
long long a, b;
cin >> a >> b;
digui(a, b);
x = (x % b + b) % b;
printf("%lld\n", x);
return 0;
}