View Compilation Error

0_0_10365751_5436.cpp: In function `int mex(int)':
0_0_10365751_5436.cpp:9: error: `N' undeclared (first use this function)
0_0_10365751_5436.cpp:9: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_10365751_5436.cpp:10: error: `re' undeclared (first use this function)