foo.cpp: In function 'int main()':
foo.cpp:42:21: warning: array subscript has type 'char' [-Wchar-subscripts]
       f[o][j+dx[a[i]][k]+dx[b[i]][k]]|=f[o^1][j]<<(dy[a[i]][k]+dy[b[i]][k]);
                     ^
foo.cpp:42:33: warning: array subscript has type 'char' [-Wchar-subscripts]
       f[o][j+dx[a[i]][k]+dx[b[i]][k]]|=f[o^1][j]<<(dy[a[i]][k]+dy[b[i]][k]);
                                 ^
foo.cpp:42:59: warning: array subscript has type 'char' [-Wchar-subscripts]
       f[o][j+dx[a[i]][k]+dx[b[i]][k]]|=f[o^1][j]<<(dy[a[i]][k]+dy[b[i]][k]);
                                                           ^
foo.cpp:42:71: warning: array subscript has type 'char' [-Wchar-subscripts]
       f[o][j+dx[a[i]][k]+dx[b[i]][k]]|=f[o^1][j]<<(dy[a[i]][k]+dy[b[i]][k]);
                                                                       ^