Run-Length Encoding

You are given a non-empty string s. Your task is to implement run-length encoding on this string. In run-length encoding, consecutive occurrences of the same character are replaced by the character followed by the count of its repetitions.

For example, if s = "aaabbccca", then its run-length encoding is a3b2c3a1. Similarly, for s = "abc", the encoding is a1b1c1.

If the input string is empty, you should output an error message: Input string is empty.

The input string is provided via standard input (stdin) and the answer should be printed to standard output (stdout).

inputFormat

A single line string s read from stdin. The string may contain only alphabets. It is guaranteed that the string is non-empty for valid test cases; however, if an empty string is provided, the program should output an error message.

outputFormat

A single line string representing the run-length encoding of the input. For invalid input (empty string), output the error message Input string is empty.## sample

aaabbccca

a3b2c3a1