diff --git a/str_lib.c b/str_lib.c
index fa1d7db..439efd2 100644
--- a/str_lib.c
+++ b/str_lib.c
@@ -7,7 +7,11 @@
 int
 mystrlen(const char *s)
 {
-	// <YOURCODE>
+	int len = 0;
+	while (s[len] != '\0') {
+		len++;
+	}
+	return len;
 }
 
 /*
@@ -17,7 +21,29 @@ mystrlen(const char *s)
 int
 mystr_idx(const char *s1, const char *s2)
 {
-	// <YOURCODE>
+	if (s1 == NULL || s2 == NULL)
+	return -1;
+
+	if (s2[0] == '\0')
+	return 0;
+
+	int len1 = mystrlen(s1);
+	int len2 = mystrlen(s2);
+
+	if (len2 > len1)
+		return -1;
+
+	for (int i = 0; i <=len1 - len2; i++) {
+		int j = 0;
+		while (j < len2 && s1[i + j] == s2[j]) {
+			j++;
+		}
+		if (j == len2)
+			return i;
+	}
+
 	return -1;
 }
 
+
+