Buses in a Bustling Town

Given the day's bus departure times and the current time, find how many minutes ago the most recent bus that has already departed left. A bus scheduled exactly at the current time has not departed yet; it must be strictly earlier than the current time. If there is none, output −1; the previous day is not considered.

输入格式

This site's input: the first line contains n (0..100000), followed by n lines of HH:MM times, and the last line is the current time. Hours are 00..23 and minutes are 00..59, and all times are on the same day; the timetable may be unsorted and may contain duplicates.

输出格式

Output the number of minutes, or −1.

样例 1

输入：

3
12:30
14:00
19:55
14:30

输出：

30

样例 2

输入：

3
00:00
14:00
19:55
00:00

输出：

-1

样例 3

输入：

3
12:30
14:00
19:55
14:00

输出：

90

样例说明

Example 1: the last bus that departed left at 14:00, which is 30 minutes before 14:30.

Example 2: the 00:00 bus is exactly at the current time and has not departed yet, so the output is −1.

Example 3: the 14:00 bus has not departed yet; the previous one is 12:30, 90 minutes earlier.