Problem Description

Encrypt a message by writing it into an N×N grid row by row, then reading it diagonally from top-left to bottom-right. Handle padding and multiple diagonals.

Input Format

Two lines: message string and grid size N.

Output Format

Encrypted message read diagonally from the grid.

Constraints

• 1 ≤ message length ≤ 1000

• 1 ≤ N ≤ 50

• Pad with 'X' if message shorter than N²

• Read all diagonals from top-left to bottom-right

• Include spaces and punctuation in message

Sample Input/Output

Explanation

Fill 4×4 grid row by row with "HELLO WORLD" + padding, then read diagonally.