Here ya go. Hope you can tell your teacher what it does...

#!/usr/bin/perl
*=*j=>*-=*k=>*>=*l=>*<=*m;
while(<>){chomp;$*++;$-+=$_;($_>$>)&&($>=$_);($_<($<||=$>))&&($<=$_)}$
+-/=$*;
print"$> $- $<\n"
[download]

------
We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.