import java.util.Scanner;

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

        String[] strNumbers = scanner.nextLine().split(" ");
        int[] numbers = new int[strNumbers.length];
        for (int i = 0; i < strNumbers.length; i++) {
            numbers[i] = Integer.parseInt(strNumbers[i]);
        }
        boolean hasEqualSum = false;
        for (int i = 0; i < numbers.length; i++) {
            int leftSum = 0;
            int rigthSum = 0;

            for (int j = i - 1; j >= 0; j--) {
                leftSum += numbers[j];
            }
            for (int j = i + 1; j < numbers.length; j++) {
                rigthSum += numbers[j];
            }
            if (leftSum == rigthSum) {
                System.out.println(i);
                hasEqualSum = true;
                break;
            }
        }
        if (!hasEqualSum) {
            System.out.println("no");
        }

    }
}