diff --git a/src/arr.rs b/src/arr.rs
index 15df86f..5a21a23 100644
--- a/src/arr.rs
+++ b/src/arr.rs
@@ -1,12 +1,12 @@
-pub fn make_arr(s: &str) -> Vec<Option<i32>> {
+pub fn make_arr(s: &str) -> Vec<i32> {
     s.trim_matches(&['[', ']'][..])
         .split(',')
         .map(|x| {
             let x = x.trim();
             if x == "null" {
-                None
+                -1
             } else {
-                Some(x.parse::<i32>().unwrap())
+                x.parse::<i32>().unwrap()
             }
         })
         .collect()
diff --git a/src/main.rs b/src/main.rs
index ec310e5..ffd864d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,61 +1,44 @@
 mod arr;
 struct Solution;
 
-use crate::arr::make_matrix;
-use std::cmp::{max, min};
-use std::collections::HashSet;
-
+use crate::arr::make_arr;
 impl Solution {
-    pub fn minimum_teachings(n: i32, languages: Vec<Vec<i32>>, friendships: Vec<Vec<i32>>) -> i32 {
-        let n = n as usize;
-        let mut m = 0;
-        let languages: Vec<HashSet<i32>> = languages
-            .into_iter()
-            .map(|x| x.into_iter().collect())
-            .collect();
-        let mut ans = 1e9 as i32;
-        let mut is_friend = vec![false; friendships.len()];
-        for i in 0..friendships.len() {
-            let ua = friendships[i][0] as usize - 1;
-            let ub = friendships[i][1] as usize - 1;
-            m = max(m,ua);
-            m = max(m,ub);
-            let lang1 = &languages[ua];
-            let lang2 = &languages[ub];
-            let intersection: HashSet<_> = lang1.intersection(&lang2).cloned().collect();
-            if !intersection.is_empty() {
-                is_friend[i] = true;
-            }
+    pub fn rotate(nums: &mut Vec<i32>, k: i32) {
+        let k = k as usize % nums.len();
+        if k == 0 {
+            return;
         }
-        for lang in 1..n + 1 {
-            let mut added = vec![false; m + 1];
-            let mut temp_ans = 0;
-            for i in 0..friendships.len() {
-                if is_friend[i] {
-                    continue;
-                }
-                let ua = friendships[i][0] as usize - 1;
-                let ub = friendships[i][1] as usize - 1;
-                let lang1 = &languages[ua];
-                let lang2 = &languages[ub];
-                if !(lang1.contains(&(lang as i32)) || added[ua]) {
-                    added[ua] = true;
-                    temp_ans += 1;
-                }
-                if !(lang2.contains(&(lang as i32)) || added[ub]) {
-                    added[ub] = true;
-                    temp_ans += 1;
+        let mut temp = nums[0];
+        let mut j = k;
+        let mut count = 0;
+        let mut start = 0;
+        let mut next_start = start + 1;
+        while count < nums.len() {
+            let temp_b = nums[j];
+            nums[j] = temp;
+            temp = temp_b;
+            if j == start {
+                j = next_start;
+                start = next_start;
+                next_start = start + 1;
+                temp = nums[j];
+                if j >= k {
+                    break;
                 }
             }
-            ans = min(ans, temp_ans);
+            if j > start && j < k {
+                next_start = j + 1;
+            }
+            j += k;
+            j %= nums.len();
+            count += 1;
         }
-        ans
+        return;
     }
 }
 
 fn main() {
-    let lang = make_matrix("[[4,7,2,14,6],[15,13,6,3,2,7,10,8,12,4,9],[16],[10],[10,3],[4,12,8,1,16,5,15,17,13],[4,13,15,8,17,3,6,14,5,10],[11,4,13,8,3,14,5,7,15,6,9,17,2,16,12],[4,14,6],[16,17,9,3,11,14,10,12,1,8,13,4,5,6],[14],[7,14],[17,15,10,3,2,12,16,14,1,7,9,6,4]]");
-    let friendships = make_matrix("[[4,11],[3,5],[7,10],[10,12],[5,7],[4,5],[3,8],[1,5],[1,6],[7,8],[4,12],[2,4],[8,9],[3,10],[4,7],[5,12],[4,9],[1,4],[2,8],[1,2],[3,4],[5,10],[2,7],[1,7],[1,8],[8,10],[1,9],[1,10],[6,7],[3,7],[8,12],[7,9],[9,11],[2,5],[2,3]]");
-    let sl = Solution::minimum_teachings(17, lang, friendships);
-    println!("{:?}", sl);
+    let mut arr = make_arr("[1,2,3,4,5,6]");
+    let sl = Solution::rotate(&mut arr, 4);
+    println!("{:?}", arr);
 }