foo.cpp: In function 'void Get(int, int, int, int, int)':
foo.cpp:18:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int mid=L+R>>1,opmid=min(mid,opl+opr);
          ~^~
foo.cpp: In function 'int main()':
foo.cpp:49:23: warning: array subscript has type 'char' [-Wchar-subscripts]
       f[now][j+dx[a[i]][k]+dx[b[i]][k]]|=f[last][j]<<(dy[a[i]][k]+dy[b[i]][k]);
                       ^
foo.cpp:49:35: warning: array subscript has type 'char' [-Wchar-subscripts]
       f[now][j+dx[a[i]][k]+dx[b[i]][k]]|=f[last][j]<<(dy[a[i]][k]+dy[b[i]][k]);
                                   ^
foo.cpp:49:62: warning: array subscript has type 'char' [-Wchar-subscripts]
       f[now][j+dx[a[i]][k]+dx[b[i]][k]]|=f[last][j]<<(dy[a[i]][k]+dy[b[i]][k]);
                                                              ^
foo.cpp:49:74: warning: array subscript has type 'char' [-Wchar-subscripts]
       f[now][j+dx[a[i]][k]+dx[b[i]][k]]|=f[last][j]<<(dy[a[i]][k]+dy[b[i]][k]);
                                                                          ^
foo.cpp: In function 'void Get(int, int, int, int, int)':
foo.cpp:26:22: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
  Get(x,L,mid-1,opl,b);
                      ^