View Compilation Error

0_0_10771426_28522.cpp: In function `int main(int, const char**)':
0_0_10771426_28522.cpp:69: error: `sum' undeclared (first use this function)
0_0_10771426_28522.cpp:69: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_10771426_28522.cpp:71: error: `ans' undeclared (first use this function)