View Compilation Error

0_0_4262438_13309.cpp: In function `int main()':
0_0_4262438_13309.cpp:7: error: `ra' undeclared (first use this function)
0_0_4262438_13309.cpp:7: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_4262438_13309.cpp:7: error: `rb' undeclared (first use this function)
0_0_4262438_13309.cpp:8: error: `ans' undeclared (first use this function)