View Compilation Error

0_0_31315835_27148.cpp: In function 'void PreDFS(int, int)':
0_0_31315835_27148.cpp:28:11: error: 'f' was not declared in this scope
   else if(f
           ^
0_0_31315835_27148.cpp:28:11: error: expected ')' at end of input
0_0_31315835_27148.cpp:28:11: error: expected statement at end of input
0_0_31315835_27148.cpp:28:11: error: expected '}' at end of input
0_0_31315835_27148.cpp:28:11: error: expected '}' at end of input