View Compilation Error

0_0_8293295_18068.cpp:2: error: `main' must return `int'
0_0_8293295_18068.cpp: In function `int main(...)':
0_0_8293295_18068.cpp:3: error: `a' undeclared (first use this function)
0_0_8293295_18068.cpp:3: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_8293295_18068.cpp:3: error: `B' undeclared (first use this function)
0_0_8293295_18068.cpp:4: error: `b' undeclared (first use this function)