Compilare: user.cpp: In function ‘int solve()’: user.cpp:12:29: warning: array subscript has type ‘char’ [-Wchar-subscripts] for(auto it : s) ++freq[it]; ^ user.cpp:14:13: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(!freq[a] && !freq[b]) return s.size(); ^ user.cpp:14:25: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(!freq[a] && !freq[b]) return s.size(); ^ user.cpp:15:13: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(!freq[c] && !freq[a]) return s.size(); ^ user.cpp:15:25: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(!freq[c] && !freq[a]) return s.size(); ^ user.cpp:16:13: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(!freq[c] && !freq[b]) return s.size(); ^ user.cpp:16:25: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(!freq[c] && !freq[b]) return s.size(); ^ user.cpp:18:17: warning: array subscript has type ‘char’ [-Wchar-subscripts] int x = freq[a] & 1; ^ user.cpp:19:17: warning: array subscript has type ‘char’ [-Wchar-subscripts] int y = freq[b] & 1; ^ user.cpp:20:17: warning: array subscript has type ‘char’ [-Wchar-subscripts] int z = freq[c] & 1; ^