u/Automatic-Dark-2050

I’m trying to figure out how to get these screws/nails(they seem like a hybrid?) out of this wood, the head is imbedded at least a quarter inch in each screw, I got the crowbar in, but I can’t figure out how to anchor it to anything to push against. I was thinking about trying to get a jigsaw in with a metal cutting blade, but I would appreciate any other ideas hopefully preventing unnecessary damage the wood I have a :lot/of planks like this doubled up