连接的时候显示出错信息:LNK2001: unresolved external symbol _ExitProcess@4

title add and subtract
include Irvine32.inc
.code
main proc
     mov eax,10000h
    add eax,40000h
    sub eax,20000h
      exit
    main endp
end main
连接的时候显示出错信息:LNK2001: unresolved external symbol _ExitProcess@4
是怎么回事啊?望指教!