LLVM 5.0 Error

I use an mac pro OSX 10.9.4 and XCODE 5.1.1 .

The problem is:

when I delete lines of code in function main, and then compile I get an error :built failed and Apple LLVM 5.0 error.

I search and get an advice to modifying system header, etc.

I am new in programming and I am not confident with my abilities.

Can I have an answer to solve it step bystep?

Thank you