How do I determine how much social security and medicare taxes I am obligated to pay?

I am currently a student with very minimal income. Last year I informed my employer of my tax-exempt status and nothing was taken out of my paycheck for federal income tax, social security or medicare. Now my income is a bit higher, so I don't have the tax-exempt status, and taxes have been taken out of my paycheck. I started paying SS and medicare tax immediately after I changed my tax-exempt status with my employer. I started preparing my tax return and noticed that there is nowhere to enter the amount that I paid for these taxes (it only asks about federal income tax paid). So how do I make sure that I paid the correct amount? If I had changed my status a week earlier or later, I would have paid a different amount, so it seems unlikely that I paid the correct amount.