Problem 9. Matrix of Numbers

// Problem 9. Matrix of Numbers
//
// Write a program that reads from the console a positive integer
// number n (1 ≤ n ≤ 20) and prints a matrix like in the examples below.
// Use two nested loops.
//
//     Examples:
// n    matrix
// 2    1 2
//      2 3
//
// n    matrix
// 3    1 2 3
//      2 3 4
//      3 4 5
//
// n    matrix
// 4    1 2 3 4
//      2 3 4 5
//      3 4 5 6
//      4 5 6 7
let input = ['3'];

let print = this.print || console.log;
let gets = this.gets || ((arr, index) => () => arr[index++])(input, 0)

let num = +gets();
let matrix = '';
let counter = 0;

for(let i = 1; i <= num; i++){
    for (let i = 1; i < num + 1; i++){
        matrix += counter + i;
    }
    counter += 1;
    console.log(matrix);
    matrix = '';
}