function solve(arr) {

    let result = 'no';

    for (let i = 0; i < arr.length ; i++) {

        let leftSum = 0;
        let rightSum = 0;

        for (let j = 0; j < arr.indexOf(arr[i]); j++) {
            leftSum += arr[j];
        }

        for (let k = arr.length - 1; k > arr.indexOf(arr[i]); k--) {
            rightSum += arr[k];
        }

        if (leftSum === rightSum){
            result = i;
            break;
        }
    }

    console.log(result);
}