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

int main() {

  int N=1000000;
  int i;
  double sum=0.0;
  for(i=0; i<N; i++) {
    double x = 1+1.0/N*i;
    sum = sum+1.0/x/N;
  }
  printf ("result is %g\n", pow(2, 1.0/sum));
  return 0;
}