String to Integer (atoi)

Convert a string to a 32-bit signed integer, the way C's atoi does:

1. Skip leading spaces.
2. Read an optional + or - sign (at most one).
3. Read digits until the first non-digit character or the end of the string. Everything after that is ignored. If no digits were read, the result is 0.
4. Apply the sign. If the number is outside the 32-bit range [−2³¹, 2³¹ − 1], clamp it: below the range → −2147483648, above → 2147483647.

Input: one line s (letters, digits, spaces, +, - and .; it contains at least one non-space character).

Output: the resulting integer.

Constraints: 1 ≤ length of s ≤ 200.

Examples: 42 → 42; -042 → -42; 1337c0d3 → 1337; 0-1 → 0; words 987 → 0; -91283472332 → -2147483648.