Compilare: user.cpp: In function ‘int main()’: user.cpp:14:16: warning: array subscript has type ‘char’ [-Wchar-subscripts] fr[a[i]]++; ^ user.cpp:15:19: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(fr[a[i]]==1) ^ user.cpp:19:26: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(fr[a[j]]>1) ^ user.cpp:21:24: warning: array subscript has type ‘char’ [-Wchar-subscripts] fr[a[j]]--; ^ user.cpp:24:20: warning: array subscript has type ‘char’ [-Wchar-subscripts] fr[a[j]]--; ^