#include <stdio.h>
#include <math.h>

int main(){
  int i, c, n;
  double x;
  scanf("%d", &n);
  c = -1;
  x = 0;
  for(i=1;i<=6;i++){
    c *= i-7;
    c /= i;
    x += c * pow(1-i/6.0, n);
  }
  printf("%.10f\n", 1-x);
  
  return 0;
}