I had sex the day I ovulated but?

My LMP was December 8th 2010. I have a normal 27 day cycle. I had been having unprotected sex with a guy for a month straight, he was finishing inside of me each time. I had sex with a different guy (i know stupid, save the rude comments) 4 days after my period ended, but he pulled out. I am due September 14th, which means i ovulated December 22nd. I had sex with the main guy on this day and every day that week with him finishing in me. What are the chances my baby is the guys I had sex with only once?