C :

#include <stdio.h>
int main()
{int k,n=0;
double Sn=0;//这道题的关键在于定义Sn为double，如果是float只过60%的数据
scanf("%d",&k);
while(Sn<=k)
{n++;
Sn+=1.0/n;//注意分子或分母必须有小数点
} 
printf("%d",n);
}

Java :

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner input=new Scanner (System.in);
		int k=input.nextInt();
		double a=0;
		int i=0;
		while(a>=0){
			a+=(double)1/(i+1);
			i++;
			if(a>k) {
				System.out.println(i);
				a=-1;
			}
			}
		}
	}