View Code of Problem 48

//2 3 5 8 13
//1 2 3 5 
#include<stdio.h>
int main(){
  int n;
  int pre = 1, cur = 2, sum;
  double result = 0;
  scanf("%d", &n);
  while(n--){
    result += (double)cur/pre;
    sum = cur+pre;
    pre = cur;
    cur = sum;
  }
  printf("%.6f", result);
  return 0;
}