Compilare: main.cpp: In function 'int main()': main.cpp:20:16: warning: array subscript has type 'char' [-Wchar-subscripts] f[c]++; ^ main.cpp:33:66: warning: array subscript has type 'char' [-Wchar-subscripts] if((b[i][j]-b[i-m][j]-b[i][j-m]+b[i-m][j-m])!=f[c]){ ^ main.cpp:33:66: warning: array subscript is above array bounds [-Warray-bounds] if((b[i][j]-b[i-m][j]-b[i][j-m]+b[i-m][j-m])!=f[c]){ ~~~^