Countdown to rocket launch

Script

#!/usr/bin/perl

print ("Enter the number of seconds left to launch the rocket: ");
$counter = <STDIN>;
chop ($counter);

until ($counter < 0)
{
        print ("The number of seconds left is: $counter \n");
        system ("sleep 1");
        $counter = $counter - 1;
}
print ("The rocket is launched !!! \n");

Execution

Enter the number of seconds left to launch the rocket: 60
The number of seconds left is: 60
The number of seconds left is: 59
The number of seconds left is: 58
The number of seconds left is: 57
The number of seconds left is: 56
The number of seconds left is: 55
The number of seconds left is: 54
The number of seconds left is: 53
The number of seconds left is: 52
The number of seconds left is: 51
The number of seconds left is: 50
The number of seconds left is: 49
The number of seconds left is: 48
The number of seconds left is: 47
The number of seconds left is: 46
The number of seconds left is: 45
The number of seconds left is: 44
The number of seconds left is: 43
The number of seconds left is: 42
The number of seconds left is: 41
The number of seconds left is: 40
The number of seconds left is: 39
The number of seconds left is: 38
The number of seconds left is: 37
The number of seconds left is: 36
The number of seconds left is: 35
The number of seconds left is: 34
The number of seconds left is: 33
The number of seconds left is: 32
The number of seconds left is: 31
The number of seconds left is: 30
The number of seconds left is: 29
The number of seconds left is: 28
The number of seconds left is: 27
The number of seconds left is: 26
The number of seconds left is: 25
The number of seconds left is: 24
The number of seconds left is: 23
The number of seconds left is: 22
The number of seconds left is: 21
The number of seconds left is: 20
The number of seconds left is: 19
The number of seconds left is: 18
The number of seconds left is: 17
The number of seconds left is: 16
The number of seconds left is: 15
The number of seconds left is: 14
The number of seconds left is: 13
The number of seconds left is: 12
The number of seconds left is: 11
The number of seconds left is: 10
The number of seconds left is: 9
The number of seconds left is: 8
The number of seconds left is: 7
The number of seconds left is: 6
The number of seconds left is: 5
The number of seconds left is: 4
The number of seconds left is: 3
The number of seconds left is: 2
The number of seconds left is: 1
The number of seconds left is: 0
The rocket is launched !!!