Compilare: main.cpp: In function 'int main()': main.cpp:16:11: warning: array subscript has type 'char' [-Wchar-subscripts] 16 | fr[c[1]] = 1; | ~~~^ main.cpp:27:20: warning: array subscript has type 'char' [-Wchar-subscripts] 27 | fr[c[dr]] ++; | ~~~~^ main.cpp:32:24: warning: array subscript has type 'char' [-Wchar-subscripts] 32 | fr[c[st - 1]] --; | ~~~~~~~~^ main.cpp:43:20: warning: array subscript has type 'char' [-Wchar-subscripts] 43 | fr[c[dr]] ++; | ~~~~^