HDOJ-2011

#include<iostream>
#include<cstdio>
using namespace std;
int main(){
    int m,n,i;
    float sum;
    while(cin>>m){
        while(m--){
            cin>>n;
            sum = 0;
            for(i=1;i<=n;i++)
            {
                if(i%2 == 0){
                    sum -= (float)1/i;
                }
                else
                    sum += (float)1/i;
            }
            printf("%.2lf\n",sum);
        }
    }    
    return 0; 
 }