4번

package JavaFestival;

import java.util.Scanner;

public class jar4 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		int num=0;
		
		for(int i=1; i<=100; i++) {
			if(i%2==0) {
				num+=-i;
			}else {
				num+=i;
			}
		}
		System.out.println("결과 : " + num);
	}
}