#include <cstdio>
#include <iostream>

using namespace std;

const int Mod = 1e9 + 7;

int a;
int m;
long long res = 1;

void ParseIn () {

    freopen ("LCG.in", "r", stdin);
    freopen ("LCG.out", "w", stdout);

    cin >> a >> m;

}

void Core () {
    
    for (int i = 1; i < m; i++) {
        res *= i; 
    }

}

void CWriteOut () {

    cout << res << endl;

}

int main () {

    ParseIn ();
    Core ();
    CWriteOut ();

    return 0;
}