Problem Description
从a点b分到s点t分时针和分针重合多少次?
Input
有多组数据,每组1行4个数 a,b,s,t. 1<=a,s <=12, 0<=b,t<60. 0 0 0 0结束.
Output
参看Sample output
Sample Input
12 50 1 2
3 8 3 20
2 45 11 0
11 0 3 20
1 2 12 50
3 20 3 8
0 0 0 0
Sample Output
0
1
8
4
11
10