Compilare: main.cpp: In function 'int main()': main.cpp:19:32: warning: array subscript has type 'char' [-Wchar-subscripts] 19 | a[x1][y1] ^= (1 << bit[ch]); | ^~ main.cpp:20:36: warning: array subscript has type 'char' [-Wchar-subscripts] 20 | a[x1][y2 + 1] ^= (1 << bit[ch]); | ^~ main.cpp:21:36: warning: array subscript has type 'char' [-Wchar-subscripts] 21 | a[x2 + 1][y1] ^= (1 << bit[ch]); | ^~ main.cpp:22:40: warning: array subscript has type 'char' [-Wchar-subscripts] 22 | a[x2 + 1][y2 + 1] ^= (1 << bit[ch]); | ^~