Meging and Squashing with strings

let n = +gets();

let arr = [];
for (let i = 1; i <= n; i++) {
    let num = gets().toString();
    arr.push(num)
}

let mergedNum = '';
let squashedNum; // any type
const mergedArr = [];
const squashedArr = [];

for (let i = 0; i < arr.length - 1; i++) {

    mergedNum = arr[i].charAt(1) + arr[i + 1].charAt(0);
    mergedArr.push(mergedNum);
}



print(mergedArr.join(' '));

for (let i = 0; i < arr.length - 1; i++) {

    let sum = 0;

    const sumPart1 = parseInt(arr[i].charAt(1));
    const sumPart2 = parseInt(arr[i + 1].charAt(0));
    sum += (sumPart1 + sumPart2) % 10;

    squashedNum = arr[i].charAt(0) + sum + arr[i + 1].charAt(1);

    squashedArr.push(squashedNum);
}

print(squashedArr.join(' '));