[Dana] gcd with unorthodox coding (#60)

---------

Co-authored-by: Kostis Sagonas <kostis@cs.ntua.gr>

Author: dion-adam

dana/programs/gcd.dana

@@ -0,0 +1,26 @@
+def main
+
+  def gcd is int: a b as int
+    if b ==     0: return: a
+    else:
+    begin
+    var s is int 
+    s := gcd: b, a % b
+    return: s
+    end
+
+  var n1 n2 is int
+  (* just messing around *)   var d is int
+  
+  writeString: "Give me two positive integers: \n"
+  n1 := readInteger()
+  n2 := readInteger()
+
+  # Making sure numbers are non-negative 
+  
+  if n1 < 0: n1 := -n1
+  if not n2 >= 0: n2 := -n2 
+  d := gcd(n1, n2)
+  writeString: "\nTheir GCD is: "
+  writeInteger: d
+  writeString: "\n"