function solve(input) {

    let N = Number(input[0]);

    let merged = '';
    let squashed = '';

    for (let i = 1; i < N; i++) {
        let a = input[i].toString().split('').map(Number);
        let b = input[i + 1].toString().split('').map(Number);

        merged += a[1].toString() + b[0].toString() + ' ';

        let c = a[1] + b[0];
        if (c >= 10) {
            c = c.toString()
            c = c[1];
        }
        squashed += a[0].toString() + c.toString() + b[1].toString() + ' ';
    }
    console.log(merged)
    console.log(squashed)
}
solve([4,
    12,
    23,
    34,
    45
])
solve([5,
    11,
    22,
    11,
    22,
    11
]);
solve([11,
    44,
    69,
    46,
    63,
    83,
    13,
    62,
    14,
    31,
    68,
    87
])