View Compilation Error

0_0_10742761_14188.cpp: In function `LL C(int, int)':
0_0_10742761_14188.cpp:30: error: `fo' undeclared (first use this function)
0_0_10742761_14188.cpp:30: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_10742761_14188.cpp:30: error: expected `;' at end of input
0_0_10742761_14188.cpp:30: error: expected `}' at end of input