Merge remote-tracking branch 'upstream/master'

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diff --git a/challenge-102/paulo-custodio/lua/ch-1.lua b/challenge-102/paulo-custodio/lua/ch-1.lua
new file mode 100644
index 0000000000..a24f601c57
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+++ b/challenge-102/paulo-custodio/lua/ch-1.lua
@@ -0,0 +1,43 @@
+#!/usr/bin/env lua
+
+--[[
+Challenge 102
+
+TASK #1 › Rare Numbers
+Submitted by: Mohammad S Anwar
+
+You are given a positive integer $N.
+
+Write a script to generate all Rare numbers of size $N if exists. Please
+checkout the page for more information about it.
+Examples
+
+(a) 2 digits: 65
+(b) 6 digits: 621770
+(c) 9 digits: 281089082
+--]]
+
+function perfect_square(n)
+    local sq = math.sqrt(n)
+    if math.floor(sq) == sq then
+        return true
+    else
+        return false
+    end
+end
+
+function print_rare(n)
+    for r=10^(n-1),(10^n)-1 do
+        r = math.floor(r)           -- convert to int
+        r1 = tonumber(string.reverse(tostring(r)))
+        if perfect_square(r+r1) then
+            if r >= r1 then
+                if perfect_square(r-r1) then
+                    io.write(r, "\n")
+                end
+            end
+        end
+    end
+end
+
+print_rare(tonumber(arg[1]))
diff --git a/challenge-102/paulo-custodio/lua/ch-2.lua b/challenge-102/paulo-custodio/lua/ch-2.lua
new file mode 100644
index 0000000000..72d378f496
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+++ b/challenge-102/paulo-custodio/lua/ch-2.lua
@@ -0,0 +1,46 @@
+#!/usr/bin/env lua
+
+--[[
+Challenge 102
+
+TASK #2 > Hash-counting String
+Submitted by: Stuart Little
+
+You are given a positive integer $N.
+
+Write a script to produce Hash-counting string of that length.
+
+The definition of a hash-counting string is as follows:
+- the string consists only of digits 0-9 and hashes, '#'
+- there are no two consecutive hashes: '##' does not appear in your string
+- the last character is a hash
+- the number immediately preceding each hash (if it exists) is the position
+of that hash in the string, with the position being counted up from 1
+
+It can be shown that for every positive integer N there is exactly one such
+length-N string.
+Examples:
+
+(a) "#" is the counting string of length 1
+(b) "2#" is the counting string of length 2
+(c) "#3#" is the string of length 3
+(d) "#3#5#7#10#" is the string of length 10
+(e) "2#4#6#8#11#14#" is the string of length 14
+--]]
+
+function hash_counting(n)
+    local out, i = '', n
+    while i > 0 do
+        p = i
+        out = '#'..out
+        i = i - 1
+        while i > 0 and p ~= 0 do
+            out = tostring(p % 10)..out
+            i = i - 1
+            p = math.floor(p / 10)
+        end
+    end
+    return out
+end
+
+print(hash_counting(tonumber(arg[1])))