乘法逆元

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;

long long min(long long a,long long b)
{
    if(a>b)return b;
    else return a;
}

int main()
{
    long long n,m;
    cin>>m>>n;
    long long ans=1000000000;
    for(long long i=1;i<n;++i)
    {
        if(i*m%n==1)ans=min(ans,i);
    }
    cout<<ans;
    puts("");
    return 0;
}

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
long long x,y;
void ex_gcd(int a,int b)
{
    if(b==0)
    {
        x=1;
        y=0;
        return;
    }
    ex_gcd(b,a%b);
    int temp=x;
    x=y;
    y=temp-a/b*y;
}

int main()
{
    long long n,m;
    scanf("%lld%lld",&n,&m);
    ex_gcd(n,m);
    printf("%lld",(x%m+m)%m);
    puts("");
    return 0;
}