View Compilation Error

298585_0_28892.cpp: In function `int main()':
298585_0_28892.cpp:42: error: `sum' undeclared (first use this function)
298585_0_28892.cpp:42: error: (Each undeclared identifier is reported only once for each function it appears in.)
298585_0_28892.cpp:56: error: expected `}' at end of input