Classes A, B, and C go rowing in the park. There are 49 students in Class A, 56 students in Class B, and 63 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 needed.
甲、乙、丙三个班的同学去公园划船，甲班49人，乙班56人，丙班63人，把各班同学分别分成小组，乘坐若干条小船，使每条船上人数相等，最少需要多少条船．
<result>7</result>