toanant · January 30, 2017 11:25 · Jan 30, 2017
diff --git a/circular_prime.py b/circular_prime.py
@@ -0,0 +1,33 @@
+#! /usr/bin/python
+
+def is_prime(n):
+    if (n == 2) or (n == 3):
+        return True
+    if (n < 2) or (n %2 == 0):
+        return False
+    if n < 9:
+        return True
+    if n % 3 == 0:
+        return False
+    sqrt_n = int(n ** 0.5)
+    step = 5
+    while step <= sqrt_n:
+        if n % step == 0:
+            return False
+        if n % (step + 2) == 0:
+            return False
+        step += 6
+    return True
+
+
+def is_circular_prime(n):
+    num = str(n)
+    for i in range(len(num)):
+        if not is_prime(int(num[i:] + num[:i])):
+            return False
+    return True
+
+if __name__ == '__main__':
+    num = int(input())
+    result = (sum(1 for n in range(2, num) if is_circular_prime(n)))
+    print(result)