bool is_lower(char ch) {

return ch >='a' && ch <='z';

}

bool is_upper(char ch) {

return ch >='A' && ch <='Z';

}

bool is_alpha(char ch) {

return is_lower(ch) || is_upper(ch);

}

bool detectCapitalUse(string word) {

bool all_upper = true, all_lower = true, first = is_upper(word[0]);

for(int i=1; i<word.size(); i++) {

if (is_lower(word[i])) all_upper = false;

if (is_upper(word[i])) all_lower = false;

}

return all_lower || first && all_upper;

}