#include <iostream.h>
#include <stdio.h>

int a[]={2,1,2,3,4,5,6,7,8,9};
float f(int n)
{
    if(1==n)
        return (float)a[0];
    else
        return((float)((n-1)*f(n-1)+a[n-1])/n);
}

main()
{
    int n=5;
    printf("f(%d)=%f\n",n,f(n));

}