A11499. Jamie and Alarm Snooze

Jamie loves sleeping. One day, he decides that he needs to wake up at exactly $hh:mm$ . However, he hates waking up, so he wants to make waking up less painful by setting the alarm at a lucky time. He will then press the snooze button every $x$ minutes until $hh:mm$ is reached, and only then he will wake up. He wants to know what is the smallest number of times he needs to press the snooze button.

A time is considered lucky if it contains a digit ' $7$ '. For example, $13:07$ and $17:27$ are lucky, while $00:48$ and $21:34$ are not lucky.

Note that it is not necessary that the time set for the alarm and the wake-up time are on the same day. It is guaranteed that there is a lucky time Jamie can set so that he can wake at $hh:mm$ .

Formally, find the smallest possible non-negative integer $y$ such that the time representation of the time $x·y$ minutes before $hh:mm$ contains the digit ' $7$ '.

Jamie uses 24-hours clock, so after $23:59$ comes $00:00$ .

The first line contains a single integer $x$ ( $1<=x<=60$ ).

The second line contains two two-digit integers, $hh$ and $mm$ ( $00<=hh<=23,00<=mm<=59$ ).

Print the minimum number of times he needs to press the button.

In the first sample, Jamie needs to wake up at 11:23. So, he can set his alarm at 11:17. He would press the snooze button when the alarm rings at 11:17 and at 11:20.

In the second sample, Jamie can set his alarm at exactly at 01:07 which is lucky.