链接:http://www.51nod.com/Challenge/Problem.html#!#problemId=1256
#include<iostream>
using namespace std;
void egcd(long long a,long long b,long long &x,long long &y){
if(b == 0){
x = 1;
y = 0;
return;
}
egcd(b,a%b,x,y);
int tmp = x;
x = y;
y = tmp - (a/b)*y;
}
int main(){
long long m,n,x,y;
cin>>m>>n;
egcd(m,n,x,y);
if(x < 0){
x += n;
}
cout<<x<<endl;
return 0;
}