View Compilation Error

258798_0_14310.c: In function `main':
258798_0_14310.c:4: error: `a' undeclared (first use in this function)
258798_0_14310.c:4: error: (Each undeclared identifier is reported only once
258798_0_14310.c:4: error: for each function it appears in.)
258798_0_14310.c:4: error: `b' undeclared (first use in this function)