#include<stdio.h>

int main(){

FILE *file1, *file2;
int N, K, nFactorial = 1, i;

file1 = fopen("kperm.in", "r");
file2 = fopen("kperm.out", "w");

fscanf(file1, "%d", &N);
fscanf(file1, "%d", &K);

if(!(K%2)){
    fprintf(file2, "0");
}else if(K==N){
    for(i=2; i<=N; i++){
        nFactorial *= i;
    }
    fprintf(file2, "%d", nFactorial);
}else{
    while(1){}
}

return 0;
}