题解

#pragma message("A30836.This file is written by C language.")
extern "C"{
    #include<stdio.h>
    int n;double sum=0.0;
    int main(){
        scanf("%d",&n);
        for (int i=1;i<=n;i++){
            sum+=(1./i);
        }
        printf("%.3lf",sum);
        return 0;
    }
}