Integers less than 2 (especially 1) are not prime.

mhayter · adamant-pwn · commit 1359569371fc · 2023-04-16T11:39:57.000+02:00
I got a wrong answer because I copied this on a contest once. This corrects the error.
diff --git a/src/algebra/primality_tests.md b/src/algebra/primality_tests.md
@@ -20,6 +20,7 @@ If it is a divisor, than $n$ is definitely not prime, otherwise it is.
 
 ```cpp
 bool isPrime(int x) {
+    if (x<2) return false;
     for (int d = 2; d * d <= x; d++) {
         if (x % d == 0)
             return false;
