Compilare: main.cpp: In function 'int main()': main.cpp:43:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); ++i) { ~~^~~~~~~~~~ main.cpp:45:19: warning: array subscript has type 'char' [-Wchar-subscripts] if (o[s[i]] == 1) { ^ main.cpp:49:47: warning: array subscript has type 'char' [-Wchar-subscripts] if (!st.empty() && tip[s[st.top()]] == tip[s[i]]) { ^ main.cpp:49:60: warning: array subscript has type 'char' [-Wchar-subscripts] if (!st.empty() && tip[s[st.top()]] == tip[s[i]]) { ^ main.cpp:60:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); ++i) { ~~^~~~~~~~~~