E06EqualSum

import java.util.Scanner;

public class E06EqualSum {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        String[] input = scanner.nextLine().split(" ");
        int[] arr = new int[input.length];

        int sumRight = 0;
        int sumLeft = 0;
        int index = 0;
        boolean isNotEqual = false;


        for (int i = 0; i < input.length; i++) {
            arr[i] = Integer.parseInt(input[i]);
        }

        for (int i = 0; i < input.length; i++) {
            index = i;
            if (i > 0) {
                sumLeft += arr[i - 1];
                for (int j = i + 1; j < input.length; j++) {
                    sumRight += arr[j];
                }
                if (sumLeft == sumRight) {
                    System.out.println(index);
                    return;
                } else if(sumLeft != sumRight) {
                    isNotEqual = true;
                }
                sumRight = 0;
            }
        }
        if (index == 0) {
            System.out.println(index);
        }
        if (isNotEqual){
            System.out.println("no");
        }
    }
}