diff --git a/14/14.py b/14/14.py
new file mode 100755
index 0000000..9825834
--- /dev/null
+++ b/14/14.py
@@ -0,0 +1,45 @@
+#!/usr/bin/env python
+# 2021 - Advent Of Code - 14
+
+from collections import Counter
+
+
+def parse_file(file):
+    with open(file) as f:
+        poly_string = list(f.readline().strip())
+        f.readline()
+        insertion_rules = dict([line.strip().split(' -> ') for line in f.readlines()])
+
+        return poly_string, insertion_rules
+
+
+def step_poly(poly_str, ruleset):
+    new_p = []
+    for i, p in enumerate(poly_str):
+        if i + 1 == len(poly_str):
+            break
+        new_p.append(p)
+        binome = '' + p + poly_str[i+1]
+        # print(f'binome {binome}')
+        found = ruleset.get(binome)
+        if found:
+            # print(f'found: {found}')
+            new_p.append(found)
+
+    new_p.append(p)
+    return ''.join(new_p)
+
+
+# poly, rules = parse_file('input_example.txt')
+poly, rules = parse_file('input.txt')
+print(f'poly: {poly}')
+print(f'rules: {rules}')
+
+for s in range(10):
+    print(f'step: {s}')
+    poly = step_poly(poly, rules)
+    print(poly)
+
+print(Counter(poly))
+c = Counter(poly).most_common()[0][1] - Counter(poly).most_common()[-1][1]
+print(c)
diff --git a/14/input.txt b/14/input.txt
new file mode 100644
index 0000000..ac9c0aa
--- /dev/null
+++ b/14/input.txt
@@ -0,0 +1,102 @@
+BCHCKFFHSKPBSNVVKVSK
+
+OV -> V
+CO -> V
+CS -> O
+NP -> H
+HH -> P
+KO -> F
+VO -> B
+SP -> O
+CB -> N
+SB -> F
+CF -> S
+KS -> P
+OH -> H
+NN -> O
+SF -> K
+FH -> F
+VV -> B
+VH -> O
+BV -> V
+KF -> K
+CC -> F
+NF -> H
+VS -> O
+SK -> K
+HV -> O
+CK -> K
+VP -> F
+HP -> S
+CN -> K
+OB -> H
+NS -> F
+PS -> S
+KB -> S
+VF -> S
+FP -> H
+BB -> N
+HF -> V
+CH -> N
+BH -> F
+KK -> B
+OO -> N
+NO -> K
+BP -> K
+KH -> P
+KN -> P
+OF -> B
+VC -> F
+NK -> F
+ON -> O
+OC -> P
+VK -> O
+SH -> C
+NH -> C
+FB -> B
+FC -> K
+OP -> O
+PV -> V
+BN -> V
+PC -> K
+PK -> S
+FF -> C
+SV -> S
+HK -> H
+NB -> C
+OK -> C
+PH -> B
+SO -> O
+PP -> F
+KV -> V
+FO -> B
+FN -> H
+HN -> C
+VB -> K
+CV -> O
+BC -> C
+CP -> S
+FS -> S
+KP -> V
+BS -> V
+BK -> B
+PN -> C
+PF -> S
+HO -> V
+NC -> N
+SS -> N
+BO -> P
+BF -> N
+NV -> P
+PB -> K
+HB -> H
+VN -> H
+FV -> B
+FK -> K
+PO -> S
+SC -> S
+HS -> S
+KC -> F
+HC -> S
+OS -> K
+SN -> N
diff --git a/14/input_example.txt b/14/input_example.txt
new file mode 100644
index 0000000..b5594dd
--- /dev/null
+++ b/14/input_example.txt
@@ -0,0 +1,18 @@
+NNCB
+
+CH -> B
+HH -> N
+CB -> H
+NH -> C
+HB -> C
+HC -> B
+HN -> C
+NN -> C
+BH -> H
+NC -> B
+NB -> B
+BN -> B
+BB -> N
+BC -> B
+CC -> N
+CN -> C