View Compilation Error

0_0_6948465_25168.cpp: In function `void clear()':
0_0_6948465_25168.cpp:29: error: `hash' undeclared (first use this function)
0_0_6948465_25168.cpp:29: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_6948465_25168.cpp: In function `int main()':
0_0_6948465_25168.cpp:70: error: `top' undeclared (first use this function)