\(/{ax+by}\)
\(=gcd(a,b)\)
\(=gcd(b,a%b)\)
\(=gcd(b,a-(a/b)*b)\)
\(=bx'+(a-(a/b)*b)y'\)
\(=ay'+(x'-(a/b)y')b\)

\(x=y'\)
\(y=x'(a/b)y\)

#include<cstdio>
#include<algorithm>
using namespace std;
pair<int,int> exgcd(int x,int y)
{
    if(x==1&&y==0)
    return make_pair(x,y);
    pair<int,int> ans=exgcd(y,x%y);
    return make_pair(ans.second,ans.first-(x/y)*ans.second);
} 
int main()
{
    int a,b;
    scanf("%d%d",&a,&b);
    pair<int,int> ans=exgcd(a,b);
    printf("%d\n",(ans.first%b+b)%b);
    return 0;
}