Print pattern of characters (A, AB, ABC, ...) recursively.

Difficulty: Hard

Phase: 3 · Recursion

XP Reward: 30 XP

Topics: Recursion, Hard

Supported Languages: Python, JavaScript, C, C++, Java

Problem Description

Given N (1 <= N <= 26), print character triangle (row 1 'A', row 2 'AB', row N 'ABC...') recursively. Input Format: Read input from standard input (stdin). Output Format: Print the result to standard output (stdout).

Constraints

-10^9 <= N <= 10^9

Examples

Example 1

Input: 3

Output: A AB ABC

Explanation: Sample execution for input 3