View Compilation Error

989752_0_0_562.cpp:44: error: `main' must return `int'
989752_0_0_562.cpp: In function `int main(...)':
989752_0_0_562.cpp:85: error: `plus' undeclared (first use this function)
989752_0_0_562.cpp:85: error: (Each undeclared identifier is reported only once for each function it appears in.)