give string s t find number way choose nonempty substring s replace single character different character result substre substre t in word find number substring s differ substre t exactly characterfor example underline substrings computer computation differ ea valid wayreturn number substring satisfy condition aboveA substre contiguous sequence character string Example 1input s aba t babaoutput 6explanation the follow pair substring s t differ exactly 1 characteraba babaaba babaaba babaaba babaaba babaaba babaThe underlined portion substring choose s tExample 2input s ab t bbOutput 3explanation the follow pair substring s t differ 1 characterab bbab bbab bbThe underlined portion substring choose s t constraints1 slength tlength 100s t consist lowercase english letter