Compilare: user.cpp: In function ‘int main()’: user.cpp:18:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.length();i++) ^ user.cpp:20:19: warning: array subscript has type ‘char’ [-Wchar-subscripts] nrtot[s[i]]++; ^ user.cpp:25:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.length();i++) ^ user.cpp:27:17: warning: array subscript has type ‘char’ [-Wchar-subscripts] nrc[s[i]]++; ^ user.cpp:32:28: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(nrc[s[i]]-nrc[j]>1) ^ user.cpp:38:29: warning: array subscript has type ‘char’ [-Wchar-subscripts] nrc[s[i]]--; ^