View Compilation Error

0_0_8605319_27785.cpp: In function `int main()':
0_0_8605319_27785.cpp:7: error: `a0' undeclared (first use this function)
0_0_8605319_27785.cpp:7: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_8605319_27785.cpp:7: error: `b0' undeclared (first use this function)