Weird Unresolved Externals

Code:

Compiling... tictactoe.cpp Linking... tictactoe.obj : error LNK2001: unresolved external symbol __chkesp tictactoe.obj : error LNK2001: unresolved external symbol _memset LINK : error LNK2001: unresolved external symbol _WinMainCRTStartup Debug/directxfirst.exe : fatal error LNK1120: 3 unresolved externals Error executing link.exe.

Can anybody help me out with these never seen them in my life sorry for being troublesome.

Ryan