Classes A, B, and C go rowing in the park. There are 49 students in Class A, 56 students in Class B, and 42 students in Class C. Divide each class into groups and take several boats so that the number of people on each boat is equal. How many boats are there?
甲、乙、丙三班同学去公园划船，甲班49人，乙班56人，丙班42人，把各班同学分别分成小组，分乘若干条小船，使每条船上人数相等，最少要有多少条船？
<result>7</result>