function mergeArr(arr1, arr2) {
    let newArr = [];

    for (let i = 0; i < arr1.length; i++) {
        if (i % 2 == 0) {
            newArr.push(Number(arr1[i]) + Number(arr2[i]));
        } else {
            newArr.push(arr1[i] + arr2[i]);
        }


    }
    console.log(newArr.join(" - "));

}
mergeArr(['5', '15', '23', '56', '35'], ['17', '22', '87', '36', '11'])