Compilare: user.cpp: In function ‘int main()’: user.cpp:46:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(strlen(a)-2>n) ^ user.cpp:54:17: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(lit[p].empty()) ^ user.cpp:59:18: warning: array subscript has type ‘char’ [-Wchar-subscripts] poz=lit[p].back(); ^ user.cpp:60:14: warning: array subscript has type ‘char’ [-Wchar-subscripts] lit[p].pop_back(); ^