#include <stdio.h>
int main(void) {
    long int N, K, n;
    long int per = 1;
    long int com = 1;
    scanf("%ld %ld", &N, &K);
    for (n = 0; n < N; n++) {
        per *= (K - n);
    }
    com = per;
    for(n = 1; n <= N; n++) {
        com /= n;
    }
    printf("%ld\n", com);
    return 0;
}