From c344d8f6f155cca62c183327a0ccaa6e541a4bea Mon Sep 17 00:00:00 2001
From: Ayaan Khan <ayaankhan98@gmail.com>
Date: Tue, 23 Jun 2020 22:58:44 +0530
Subject: [PATCH] Multiplication result may overflow 'int' before it is
 converted to 'long'.

---
 math/primes_up_to_billion.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/math/primes_up_to_billion.cpp b/math/primes_up_to_billion.cpp
index b7377cea5..af6d34ff3 100644
--- a/math/primes_up_to_billion.cpp
+++ b/math/primes_up_to_billion.cpp
@@ -14,9 +14,9 @@ void Sieve(int64_t n) {
     memset(prime, '1', sizeof(prime));  // intitize '1' to every index
     prime[0] = '0';                     // 0 is not prime
     prime[1] = '0';                     // 1 is not prime
-    for (int64_t p = 2; p * p <= n; p++) {
+    for (long p = 2; p * p <= n; p++) {
         if (prime[p] == '1') {
-            for (int64_t i = p * p; i <= n; i += p)
+            for (long i = p * p; i <= n; i += p)
                 prime[i] = '0';  // set all multiples of p to false
         }
     }