subsequence

#include<iostream>
#include<math.h>

#define mod 1000000007

using namespace std;

long long f[100000];

long long factorial(long long x){
    if(x == 0){
        return f[x];
    }
    long long ans = ((x) * (factorial(x-1)) * 1LL) % mod;
    f[x] = ans;
    return ans;
}

int main(){
    long long  n ,m;
    cin >> n >> m;
    f[0] = 1;
    long long ans = ((factorial(n))/((f[m]) * (f[n-m]) * 1LL)) % mod;
    cout << ans;
    return 0;
}