View Compilation Error

0_0_3943847_12432.cpp: In function `int main()':
0_0_3943847_12432.cpp:13: error: `A' undeclared (first use this function)
0_0_3943847_12432.cpp:13: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_3943847_12432.cpp:13: error: `B' undeclared (first use this function)
0_0_3943847_12432.cpp:17: error: expected primary-expression before '[' token
0_0_3943847_12432.cpp:19: error: `sum' undeclared (first use this function)
0_0_3943847_12432.cpp:19: error: `a' undeclared (first use this function)
0_0_3943847_12432.cpp:24: error: expected `)' before ';' token
0_0_3943847_12432.cpp:70: error: expected `}' at end of input