逆元

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<cmath>
#include<queue>
#include<map>
#include<set>
using namespace std;

#define inf 0x3f3f3f3f
#define eps 1e-8
#define LL long long 
#define ull unsigned long long
#define MP make_pair
#define For( i, x, y ) for( int i = ( x ); i <= ( y ); ++i )
#define mxn 300200

int gcd( int a, int b ) {
	if( b == 0 )
		return a;
	return gcd( b, a % b );
}
void exgcd( int a, int b, int &x, int &y ) {
	if( b == 0 ) {
		x = 1;
		return;
	}
	int tem = x;
	x = y;
	y = tem - a / b * x;
}
int mod_inverse( int a, int m ) {
	int x, y;
	exgcd( a, m, x, y );
	return ( m + x % m ) % m;
}
int main() {
	return 0;
}