View Compilation Error

0_0_8707527_32579.cpp:16: error: `N' was not declared in this scope
0_0_8707527_32579.cpp: In function `void init()':
0_0_8707527_32579.cpp:20: error: `head' undeclared (first use this function)
0_0_8707527_32579.cpp:20: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_8707527_32579.cpp: In function `void add(int, int)':
0_0_8707527_32579.cpp:28: error: `head' undeclared (first use this function)
0_0_8707527_32579.cpp: In function `int bfs(int)':
0_0_8707527_32579.cpp:47: error: `head' undeclared (first use this function)