# This code gets the overlap between two closed ranges:
#    R1 = [$L1, $U1]
# and    R2 = [$L2, $U2]

# parameters
my $L1 = 5;
my $L2 = -33;
my $U1 = 10;
my $U2 = 10;

# result
my $common;

# if R1 ends somewhere in R2
if (($U1 >= $L2) && ($U1 <= $U2)) {
    # make sure to use smallest lower boundary
    ($L1 > $L2) ? (    $common = $U1 - $L1) : ($common = $U1 - $L2);
    $common++;
    }

# elsif R2 ends somewhere in R1
elsif (($U2 >= $L1) && ($U2 <= $U1)) {
    # make sure to use smallest lower boundary
    ($L1 > $L2) ? (    $common = $U2 - $L1) : ($common = $U2 - $L2);
    $common++;
    }

# else no match
else {
    $common = 0;
    }

print "Common: $common\n";
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