#include <stdio.h>

int main()
{
    int n,i,c;
    float p;
    scanf("%d",&n);
    p=2;c=1;
    for (i=1;i<n;i++)
    {
        c*=(i+1);
        p*=(1+ 1.0/c);
    }
    printf("%f\n",p);
    return 0;
}