View Compilation Error

0_0_37424741_30170.cpp: In function 'll c(int, int, int)':
0_0_37424741_30170.cpp:13:25: error: 'd' was not declared in this scope
   return d(l - 1, mid, g) + o(mid, r, g);
                         ^
0_0_37424741_30170.cpp:13:40: error: 'o' was not declared in this scope
   return d(l - 1, mid, g) + o(mid, r, g);
                                        ^