P15521 [CCC 2016 J4] Arrival Time

Fiona commutes to work each day. If there is no rush-hour traffic, her commute time is $2$ hours. However, there is often rush-hour traffic. Specifically, rush-hour traffic occurs from $07:00$ (7am) until $10:00$ (10am) in the morning and $15:00$ (3pm) until $19:00$ (7pm) in the afternoon. During rush-hour traffic, her speed is reduced by half. She leaves either on the hour (at XX:00), 20 minutes past the hour (at XX:20), or 40 minutes past the hour (at XX:40). Given Fiona's departure time, at what time does she arrive at work?

The input will be one line, which contains an expression of the form **HH:MM**, where **HH** is one of the 24 starting hours ($00$, $01$, ..., $23$) and **MM** is one of the three possible departure minute times ($00$, $20$, $40$).

Output the time of Fiona's arrival, in the form **HH:MM**.

**Explanation for Output for Sample Input 1** Fiona does not encounter any rush-hour traffic, and leaving at $5$am, she arrives at exactly $7$am. **Explanation for Output for Sample Input 2** Fiona drives for $3$ hours in rush-hour traffic, but only travels as far as she normally would after driving for $1.5$ hours. During the final $30$ minutes ($0.5$ hours) she is driving in non-rush-hour traffic. **Explanation for Output for Sample Input 3** Fiona leaves at $11:20$pm, and with non-rush-hour traffic, it takes two hours to travel, so she arrives at $1:20$am the next day.