Compilare: main.cpp: In function 'int main()': main.cpp:21:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); i++) ~~^~~~~~~~~~ main.cpp:26:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (isalpha(s[i]) and i < s.size()) ~~^~~~~~~~~~ main.cpp:20:9: warning: unused variable 'ok' [-Wunused-variable] int ok = 0; ^~