Around dawn on 25 October, Ozawa launched 75 aircraft to attack the 3rd Fleet. Most were shot down by American combat air patrols, and no damage was done to the U.S. ships. A few Japanese planes survived and made their way to land bases on Luzon. During the night, Halsey had passed tactical command of TF38 to Admiral Mitscher, who ordered the American carrier groups to launch their first strike wave, of 180 aircraft, at dawnbefore the Northern Force had been located. When the search aircraft made contact at 07:10, this strike wave was orbiting ahead of the task force. At 08:00, as the attack went in, its escorting fighters destroyed Ozawa's combat air patrol of about 30 planes. The U.S. air strikes continued until the evening, by which time TF38 had flown 527 sorties against the Northern Force, sinking Zuikaku, the light carriers Chitose and Zuiho, and the destroyer Akizuki, all with heavy loss of life. The light carrier Chiyoda and the cruiser Tama were crippled. Ozawa transferred his flag to the light cruiser Oyodo.
Answer this question: How many ships were sunk in the strike?
4