First Digit

Given a non-negative integer n, return the first (most-significant) digit in its decimal representation. For n = 0, return 0.

Given a non-negative integer `n`, return the first (most-significant) digit in its decimal representation. For `n = 0`, return `0`.

- `0 <= n <= 10^9` - The input has no leading zeroes except for `0` itself.

Example 1: input n = 482731; output 4. Four is the most-significant digit.

Example 2: input n = 10000; output 1. Repeated division leaves one.

Category: Math. Topic: math. Difficulty: Easy. Patterns: math.