View Compilation Error

242028_0_30188.cpp: In function `int main()':
242028_0_30188.cpp:4: error: `$a' undeclared (first use this function)
242028_0_30188.cpp:4: error: (Each undeclared identifier is reported only once for each function it appears in.)
242028_0_30188.cpp:4: error: `$b' undeclared (first use this function)