Compilare: user.cpp: In function ‘int main()’: user.cpp:13:12: warning: array subscript has type ‘char’ [-Wchar-subscripts] fr[v[dr]]++; ^ user.cpp:14:15: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(fr[v[dr]]==1) ^ user.cpp:18:19: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(fr[v[st]]>1) ^ user.cpp:20:14: warning: array subscript has type ‘char’ [-Wchar-subscripts] fr[v[st]]--; ^ user.cpp:23:13: warning: array subscript has type ‘char’ [-Wchar-subscripts] fr[v[st]]--;st++;nr--; ^