View Compilation Error

1_374_932_23024.cpp: In function `int main()':
1_374_932_23024.cpp:11: error: `a' undeclared (first use this function)
1_374_932_23024.cpp:11: error: (Each undeclared identifier is reported only once for each function it appears in.)
1_374_932_23024.cpp:11: error: `b' undeclared (first use this function)