Mr. Zhang is going to send a letter and needs 6 cents of stamps. He only has 1 cents and 2 cents of stamps. If he wants to put enough 6 cents of stamps on the envelope, how many different ways are there?
张老师准备寄一封信，需要6角的邮票，他只有1角和2角的邮票，要想在信封上贴够6角邮票，一共有多少种不同的贴法？
<result>4</result>