diff --git a/README.md b/README.md
index 36d76f79f..30a91383a 100644
--- a/README.md
+++ b/README.md
@@ -271,7 +271,7 @@ Graphics and Multimedia
 Security
 -------------
 
-**Caesar cipher** - Implement a Caesar cipher, both encoding and decoding. The key is an integer from 1 to 25. This cipher rotates the letters of the alphabet (A to Z). The encoding replaces each letter with the 1st to 25th next letter in the alphabet (wrapping Z to A). So key 2 encrypts "HI" to "JK", but key 20 encrypts "HI" to "BC". This simple "monoalphabetic substitution cipher" provides almost no security, because an attacker who has the encoded message can either use frequency analysis to guess the key, or just try all 25 keys.
+**Caesar cipher** - Implement a Caesar cipher, both encoding and decoding. The key is an integer from 1 to 26. This cipher rotates the letters of the alphabet (A to Z). The encoding replaces each letter with the 1st to 26th next letter in the alphabet (wrapping Z to A). So key 2 encrypts "HI" to "JK", but key 20 encrypts "HI" to "BC". This simple "monoalphabetic substitution cipher" provides almost no security, because an attacker who has the encoded message can either use frequency analysis to guess the key, or just try all 26 keys.
 
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diff --git a/Security/README.md b/Security/README.md
index a654b76c7..3d6941ab5 100644
--- a/Security/README.md
+++ b/Security/README.md
@@ -1,4 +1,4 @@
 Security
 -------------
 
-**Caesar cipher** - Implement a Caesar cipher, both encoding and decoding. The key is an integer from 1 to 25. This cipher rotates the letters of the alphabet (A to Z). The encoding replaces each letter with the 1st to 25th next letter in the alphabet (wrapping Z to A). So key 2 encrypts "HI" to "JK", but key 20 encrypts "HI" to "BC". This simple "monoalphabetic substitution cipher" provides almost no security, because an attacker who has the encoded message can either use frequency analysis to guess the key, or just try all 25 keys.
\ No newline at end of file
+**Caesar cipher** - Implement a Caesar cipher, both encoding and decoding. The key is an integer from 1 to 26. This cipher rotates the letters of the alphabet (A to Z). The encoding replaces each letter with the 1st to 26th next letter in the alphabet (wrapping Z to A). So key 2 encrypts "HI" to "JK", but key 20 encrypts "HI" to "BC". This simple "monoalphabetic substitution cipher" provides almost no security, because an attacker who has the encoded message can either use frequency analysis to guess the key, or just try all 26 keys.