Compilare: user.cpp: In function ‘int main()’: user.cpp:18:29: warning: array subscript has type ‘char’ [-Wchar-subscripts] for(i=1;i<=n;++i) ++fr[s[i]]; ^ user.cpp:21:16: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(fr[s[i]]==0 && i<=n) ^ user.cpp:26:16: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(fr[s[i]]>1) { ^ user.cpp:32:13: warning: array subscript has type ‘char’ [-Wchar-subscripts] --fr[s[i]]; ^ user.cpp:38:13: warning: array subscript has type ‘char’ [-Wchar-subscripts] ++fr[s[i]]; ^ user.cpp:42:12: warning: array subscript has type ‘char’ [-Wchar-subscripts] fr[bestch]=0; ^