View Compilation Error

0_0_9153726_17415.cpp: In function `void build(int, int, int)':
0_0_9153726_17415.cpp:21: error: `mid_1' undeclared (first use this function)
0_0_9153726_17415.cpp:21: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_9153726_17415.cpp: In function `void del(int, int)':
0_0_9153726_17415.cpp:24: error: `h' undeclared (first use this function)
0_0_9153726_17415.cpp:25: error: expected primary-expression before ')' token