diff --git a/day25/input.txt b/day25/input.txt
new file mode 100644
index 0000000..9235afa
--- /dev/null
+++ b/day25/input.txt
@@ -0,0 +1,2 @@
+8458505
+16050997
diff --git a/day25/part1.py b/day25/part1.py
new file mode 100644
index 0000000..86cdba6
--- /dev/null
+++ b/day25/part1.py
@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+
+c_pub, d_pub = [int(x.strip()) for x in open("input.txt")]
+
+val = 1
+less_loop, less_pub = None, None
+for loop in range(1, 20201227):
+    val = (val*7) % 20201227
+    if val == c_pub:
+        less_loop, less_pub = loop, d_pub
+        break
+    elif val == d_pub:
+        less_loop, less_pub = loop, c_pub
+        break
+
+val = 1
+for _ in range(less_loop):
+    val = (val*less_pub) % 20201227
+print(val)