C :

#include<stdio.h>
int f(int n){
	if(n==1||n==2){
		return 1;
	}else{
		return f(n-1) + f(n-2);
	}
}
void main(){
	int n,i;
	scanf("%d",&n);
	double s = 0;
	for(i=1;i<=n;i++){
		s = s + f(i)*1.0/f(i+1);
	}
	printf("%.3lf",s);
}

C++ :

#include<iostream>
#include<iomanip>
using namespace std;


int digui(int n);

int main(){
	int n=0;
	double s=0;
	cin>>n;
	
	for(int i=1;i<=n;i++){
		s=s+digui(i)*1.0/digui(i+1);
		
	}
	
	cout<<setiosflags(ios::fixed)<<setprecision(3)<<s<<endl;
}

int digui(int n){
	if(n==1 || n==2){
		return 1;
	}
	else{
		return digui(n-1)+digui(n-2);
	}
}

Pascal :

var
sum,a,b,d:real; 
c,n:longint; 
begin
read(n); 
sum:=0; 
a:=1;
b:=1; 
for c:=1 to n do 
  begin 
  sum:=sum+a/b; 
  d:=b; 
  b:=a+b; 
  a:=d; 
  end; 
  writeln(sum:0:3);
end.

Java :

import java.text.DecimalFormat;
import java.util.Scanner;
public class Main{
	public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		int n=scanner.nextInt();
		int a=1;
		int b=1;
		float sum=0;
		for(int i=0;i<n;i++){
			sum=sum+(float)a/b;
			int tmp=a;
			a=b;
			b=tmp+b;
		}
		DecimalFormat df = new DecimalFormat("#.000");
		System.out.println(df.format(sum));
	}
}

Python :

def feiBo(n):
    if n == 1 or n == 2 :
        return 1
    else:
        return feiBo(n - 1) + feiBo(n - 2);
n = int(input())
s = 0
for i in range (1,n+1):
     s += feiBo(i) / feiBo(i + 1)
print('%.3f' % s)