#include <iostream>
#include <fstream>
#define MOD 2000003
using namespace std;
long long n,k,p;

ifstream fin("sandokan.in");
ofstream fout("sandokan.out");

long long comb(long long n, long long m){
    /// comb(n, m) = aranj(n, m)/m!
    long long res = 1;
    for(long long i = n-m+1; i <= n; i++){
        res = res*i;
    }
    for(long long i = 1; i <= m; i++){
        res /= i;
    }
    return res;
}

int main()
{
    fin >> n >> k;
    p = (n-1)%(k-1)+1;
    fout << comb(n-1, p-1) << "\n";
    return 0;
}