#include<bits/stdc++.h> 
using namespace std;
typedef unsigned long long LL;
int n, m, a[110], b[110];
LL gcd(LL x, LL y){if(y==0)return x;else return gcd(y, x%y);}
LL cal(LL n, LL m) {
    m=min(m, n-m);
    LL s=1;
    for(int i=1;i<=m;i++)a[i]=n-i+1, b[i]=i;
    for(int i=1;i<=m;i++) {
        for(int j=1;j<=m;j++) {
            LL d=gcd(a[i], b[j]);
            a[i]=a[i]/d;
            b[j]=b[j]/d;
        }
        s=s*a[i];
    }
    return s;
}
int main() {
    int n, k;scanf("%d%d", &n, &k);
    LL ans=cal(n-k+1, k);
    printf("%lu", ans);
    return 0;
}