How many do you recognize?

Here are the pictures:

George Washington
John Adams
Thomas Jefferson
James Madison
James Monroe
John Quincy Adams
Andrew Jackson
Martin Van Buren
William Henry Harrison
John Tyler
James Knox Polk
Zachary Taylor
Millard Fillmore
Franklin Pierce
James Buchanan
Abraham Lincoln
Andrew Johnson
Ulysses Simpson Grant
Rutherford Birchard Hayes
James Abram Garfield
Chester Alan Arthur
Grover Cleveland
Benjamin Harrison
Grover Cleveland
William McKinley
Theodore Roosevelt
William Howard Taft
Woodrow Wilson
Warren Gamaliel Harding
Calvin Coolidge
Herbert Clark Hoover
Franklin Delano Roosevelt
Harry S. Truman
Dwight David Eisenhower
John Fitzgerald Kennedy
Lyndon Baines Johnson
Richard Milhous Nixon
Gerald Rudolph Ford
James Earl Carter, Jr.
Ronald Wilson Reagan
George Herbert Walker Bush
William Jefferson Clinton
George Walker Bush