Compilare: main.cpp: In function 'int main()': main.cpp:13:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.size();i++) ~^~~~~~~~~ main.cpp:14:26: warning: suggest parentheses around '&&' within '||' [-Wparentheses] if('a'<=s[i] and s[i]<='z' || 'A'<=s[i] and s[i]<='Z') ~~~~~~~~~~^~~~~~~~~~~~~