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diff --git a/challenge-215/jo-37/perl/ch-2.pl b/challenge-215/jo-37/perl/ch-2.pl
new file mode 100755
index 0000000000..ef6acca9b4
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+++ b/challenge-215/jo-37/perl/ch-2.pl
@@ -0,0 +1,64 @@
+#!/usr/bin/perl -s
+
+use v5.24;
+use Test2::V0 '!float';
+use PDL v2.017;
+
+our ($tests, $examples, $count);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV && $count;
+usage: $0 [-examples] [-tests] [-count=C] [N...]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+-count=C
+    check if C zeroes may be flipped
+
+N...
+    list of zeroes and ones
+
+EOS
+
+
+### Input and Output
+
+say 0 + ($count <= replace_count(@ARGV));
+
+
+### Implementation
+
+# For every two zeroes following a single leading zero, one zero may be
+# flipped.  Count sequential zeros and sum over the number of zeroes
+# that may be flipped. 
+sub replace_count {
+    my ($count, $val) = rle long @_;
+
+    sum +($count->where($val == 0) - 1) / 2;
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+
+        ok  replace_count([1,0,0,0,1], 1), 'example 1';
+        ok  replace_count([1,0,0,0,0,0,0,0,1], 3), 'example 3';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+
+        ok  replace_count([0,0,0,0,0,1,0,0,0,0,0], 4), 'two blocks of 5 zeroes';
+	}
+
+    done_testing;
+    exit;
+}