View Compilation Error

236389_0_11385.cpp: In function `int main()':
236389_0_11385.cpp:4: error: `a' undeclared (first use this function)
236389_0_11385.cpp:4: error: (Each undeclared identifier is reported only once for each function it appears in.)
236389_0_11385.cpp:4: error: `b' undeclared (first use this function)