SumsStep3

import java.util.Scanner;

public class SumsStep3 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = Integer.parseInt(scanner.nextLine());

        int sum1= 0;
        int sum2= 0;
        int sum3= 0;

        for ( int i=0; i<n; i++) {
            int a = Integer.parseInt(scanner.nextLine());
            if (i % 3==0) {
                sum1 += a;
            }
            if ( i % 3==1) {
                sum2 += a;
            }
            if ( i % 3 == 2) {
                sum3 += a;
            }
        }
        System.out.printf("sum1=%d%n", sum1);
        System.out.printf("sum2=%d%n", sum2);
        System.out.printf("sum3=%d%n", sum3);
    }
}