diff --git a/P4017/P4017.cpp b/P4017/P4017.cpp
index f23dcdb..da16799 100644
--- a/P4017/P4017.cpp
+++ b/P4017/P4017.cpp
@@ -1,9 +1,39 @@
 #include <iostream>
+#include <ranges>
+#include <queue>
 
 using std::cin,std::cout,std::iostream;
+static const constexpr auto range {std::ranges::views::iota};
+
+static const constexpr int MOD {80112002}, MAX_TYPES {(int)5e3+5}, MAX_REL_SHIPS {(int)5e5+5};
+static int types, rel_ships, a, b, in_degree[MAX_REL_SHIPS], out_degree[MAX_REL_SHIPS];
+std::queue<int> q;
+std::vector<int> next[MAX_REL_SHIPS];
 
 int main(){
     iostream::sync_with_stdio(false);
 
-    
+    cin>>types>>rel_ships;
+    for(const int _:range(1,rel_ships+1)){
+        cin>>a>>b;
+        next[a].push_back(b);
+        in_degree[b]++;
+        out_degree[a]++;
+    }
+
+    for(const int i:range(1, rel_ships+1)){
+        if(in_degree[i]==0){
+            q.push(i);
+        }
+    }
+
+    while(q.empty()==false){
+        auto front {q.front()};
+        q.pop();
+        for(auto i:next[front]){
+            if(--in_degree[i]==0){
+                q.push(i);
+            }
+        }
+    }
 }
\ No newline at end of file