View Compilation Error

0_0_6600778_20933.cpp: In function `bool check(int)':
0_0_6600778_20933.cpp:106: error: `N' undeclared (first use this function)
0_0_6600778_20933.cpp:106: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_6600778_20933.cpp: In function `int main()':
0_0_6600778_20933.cpp:127: error: `N' undeclared (first use this function)