Write a recursive function named lettersOnly that accepts a string str as a parameter and returns a string with the same characters as str, in the same order, but excluding any characters that are not alphabetic letters from A-Z, case-insensitive. For example, lettersOnly("{[[Friends, save $$$ with 'Geico' !!]]}") should return "Friends savewithGeico". Complete the following file: lettersOnly.cpp #include using namespace std; 1 2. 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 #include std::string lettersOnly(const std::string& s) { char x = s[s.length() - 1]; if (s.length() = 65 && (int) x = 97 && (int) x = 65 && (int) x = 97 && (int) x >@3\t" timeout: the monitored command dumped core /opt/codecheck/runprog: line 36: 13651 Segmentation fault timeout ${TIMEOUT}s nice $PROG $@ fail lettersOnly "!" timeout: the monitored command dumped core /opt/codecheck/runprog: line 36: 13659 Segmentation fault timeout ${TIMEOUT)s nice $PROG $@ Score 3/9