diff --git "a/T3-\354\247\200\355\231\230/2-Sorting/BOJ1427.java" "b/T3-\354\247\200\355\231\230/2-Sorting/BOJ1427.java"
index 455f7af..a605112 100644
--- "a/T3-\354\247\200\355\231\230/2-Sorting/BOJ1427.java"
+++ "b/T3-\354\247\200\355\231\230/2-Sorting/BOJ1427.java"
@@ -27,7 +27,7 @@ public static void main(String[] args) {
             int max_index = i;
             for(int j = i+1; j<count; j++){
                 int b = index[j];
-                if(b>=max){
+                if(b>max){
                     max = b;
                     max_index = j;
                     swap = true;
diff --git "a/T3-\354\247\200\355\231\230/6-Graph/BOJ2252.java" "b/T3-\354\247\200\355\231\230/6-Graph/BOJ2252.java"
new file mode 100644
index 0000000..24abecc
--- /dev/null
+++ "b/T3-\354\247\200\355\231\230/6-Graph/BOJ2252.java"
@@ -0,0 +1,38 @@
+import java.util.*;
+
+public class BOJ2252 {
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int N = sc.nextInt();
+        int M = sc.nextInt();
+        ArrayList<ArrayList<Integer>> A = new ArrayList<>();
+
+        for (int i=0; i<N+1; i++) {
+            A.add(new ArrayList<>());
+        }
+        int id[] = new int[N+1];
+
+        for (int i=0; i<M; i++) {
+            int S = sc.nextInt();
+            int E = sc.nextInt();
+            A.get(S).add(E);
+            id[E]++;
+        }
+
+        Queue<Integer> Q = new LinkedList<>();
+        for(int i=1; i<N+1; i++){
+            if(id[i]==0) Q.offer(i);
+        }
+
+        for(int i=0; i<N; i++){
+            if(Q.isEmpty()) return;
+
+            int x = Q.poll();
+            System.out.print(x+" ");
+            for (int y : A.get(x)){
+                id[y]--;
+                if(id[y]==0) Q.offer(y);
+            }
+        }
+    }
+}