View Compilation Error

40878_0_1313.cpp: In function `int main()':
40878_0_1313.cpp:7: error: `a' undeclared (first use this function)
40878_0_1313.cpp:7: error: (Each undeclared identifier is reported only once for each function it appears in.)
40878_0_1313.cpp:7: error: `b' undeclared (first use this function)