View Compilation Error

0_0_6567575_26708.cpp: In function `int main()':
0_0_6567575_26708.cpp:18: error: `visit1' undeclared (first use this function)
0_0_6567575_26708.cpp:18: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_6567575_26708.cpp:19: error: `visit2' undeclared (first use this function)