Compilare: main.cpp: In function 'int main()': main.cpp:25:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < s.size(); i++) ~~^~~~~~~~~~ main.cpp:28:19: warning: array subscript has type 'char' [-Wchar-subscripts] if (a[s[i]] == 1) ^ main.cpp:32:39: warning: array subscript has type 'char' [-Wchar-subscripts] if(!st.empty() && usu[s[i]] == usu[s[st.top()]]) ^ main.cpp:32:59: warning: array subscript has type 'char' [-Wchar-subscripts] if(!st.empty() && usu[s[i]] == usu[s[st.top()]]) ^ main.cpp:45:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < s.size(); i++) ~~^~~~~~~~~~