Kata

Problem Statement

You're given a string of digits representing a sequence of consecutive natural numbers concatenated together. Your task is to find the smallest possible first number in the sequence. The sequence starts with a single or multi-digit number and continues with numbers each incremented by 1. If multiple sequences can be formed, choose the one that starts with the smallest number.

Examples

• "123" -> [1, 2, 3] -> 1
• "91011" -> [9, 10, 11] -> 9
• "17181920" -> [17, 18, 19, 20] -> 17
• "9899100" -> [98, 99, 100] -> 98
• "91" -> [91] -> 91
• "121122123" -> [121, 122, 123] -> 121
• "1235" -> [1235] -> 1235
• "101" -> [101] -> 101

Constraints

• Input string length: 1 - 200 characters.
• Smallest possible first number: 1 - 1,000,000,000.

Remember, the key is to form a sequence of consecutive natural numbers. If the sequence matches the input string, you've found the smallest possible first number. Experiment with different lengths for the first number until you find a match or exhaust all possibilities.