1 + 29 == 30
How did you compute the length of the string?
The string consists of a single character, followed by many more characters. The total length of the string is:
length( first character of the string ) + length( all but the first character )
which is
1 + length( tail of the string )
If only we had a way to find the length of the tail of the string....
How can you figure out the length of the tail of the string?