C语言解答

#include<stdio.h>
void main(){
  int a;
  while(scanf("%d",&a)!=EOF	){
    int i,sum=0;
    for(i=1;i<a;i=i+2){
      sum=sum+i;
    }
    printf("%d\n",sum);
  }
}

C++解答

#include<iostream>
using namespace std;
int main(){
	int a;
	int result =0;
	while(cin>>a){
		for(int i=1;i<a;i+=2)
			result+=i;
		cout<<result<<endl;	
		result = 0;
	}
	return 0;
	
}

Java解答

import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        Scanner input = new Scanner(System.in);
        while(input.hasNextInt()){
            int a = input.nextInt();
            int sum = 1,x,y = 1;
            for(x = 1;x < a;x++){
                y = y + 2;
                if(y >= a)
                    break;
                else
                    sum = sum + y;
            }
            System.out.println(sum);
        }
    }
}