View Compilation Error

633860_0_0_3565.cpp: In function `int main()':
633860_0_0_3565.cpp:9: error: `a' undeclared (first use this function)
633860_0_0_3565.cpp:9: error: (Each undeclared identifier is reported only once for each function it appears in.)
633860_0_0_3565.cpp:9: error: `b' undeclared (first use this function)