how to transfer contacts in an old version of iphone

Hi community,

I had a serious question. I have a very very old Iphone 4 with 4.0 os something I guess, right now I got a iphone 5s and wish to transfer my contact information. But Itunes cannot recognize the old iphone and need to restore. My question is, is restoring old iphone 4 will delete all the information in that? Is there any other method to transfer information? I tried to use some apps but there is no app to support 4.0 OS.