View Compilation Error

0_0_10264003_1105.cpp: In function `int main()':
0_0_10264003_1105.cpp:7: error: `A' undeclared (first use this function)
0_0_10264003_1105.cpp:7: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_10264003_1105.cpp:7: error: `B' undeclared (first use this function)
0_0_10264003_1105.cpp:7: error: `n' undeclared (first use this function)