2 files changed, 27 insertions, 0 deletions
diff --git a/prolog/problems/lists/count_3/common.py b/prolog/problems/lists/count_3/common.py
new file mode 100644
index 0000000..583ad6b
--- /dev/null
+++ b/prolog/problems/lists/count_3/common.py
@@ -0,0 +1,15 @@
+id = 120
+group = 'lists'
+number = 27
+visible = True
+facts = None
+
+solution = '''\
+count(_, [], 0).
+count(X, [X|T], N) :-
+  count(X, T, NT),
+  N is NT + 1.
+count(X, [Y|T], NT) :-
+  X \== Y,
+  count(X, T, NT).
+'''
diff --git a/prolog/problems/lists/count_3/en.py b/prolog/problems/lists/count_3/en.py
new file mode 100644
index 0000000..799594e
--- /dev/null
+++ b/prolog/problems/lists/count_3/en.py
@@ -0,0 +1,12 @@
+id = 120
+name = 'count/3'
+slug = 'find the number of occurrences of an element in list'
+
+description = '''\
+<p><code>count(X, L, N)</code>: <code>N</code> is the number of times the element <code>X</code> appears in the list <code>L</code>.</p>
+<pre>
+  ?- count(1, [1,2,1,3,1], N).
+    N = 3.
+</pre>'''
+
+hint = {}