View Compilation Error

0_0_20776685_24839.cpp: In function 'int get_K(int, int)':
0_0_20776685_24839.cpp:2:16: error: 'push_down' was not declared in this scope
     push_down(r) ;
                ^
0_0_20776685_24839.cpp:3:13: error: 'num' was not declared in this scope
     int t = num[ch[r][0]] ;
             ^
0_0_20776685_24839.cpp:3:17: error: 'ch' was not declared in this scope
     int t = num[ch[r][0]] ;
                 ^