View Compilation Error

366273_0_0_22913.cpp:3: error: `main' must return `int'
366273_0_0_22913.cpp: In function `int main(...)':
366273_0_0_22913.cpp:4: error: `a' undeclared (first use this function)
366273_0_0_22913.cpp:4: error: (Each undeclared identifier is reported only once for each function it appears in.)
366273_0_0_22913.cpp:4: error: `b' undeclared (first use this function)