#include<bits/stdc++.h>
using namespace std;

int main()
{
    long long int n,r,k,i,j,a,b,c;
    double ans=0.0;
    while(cin>>n>>r)
    {
        a=min(r,n-r);
        ans=0.0;
        b=n-a+1;
        for(i=b;i<=n;i++)
            ans+=log10(i);
        for(i=1;i<=a;i++)
            ans-=log10(i);

        ans=floor(ans)+1;
        cout<<ans<<endl;
    }
    return 0;
}