diff --git a/AcWing/4003/4003.cpp b/AcWing/4003/4003.cpp
new file mode 100644
index 00000000..a25ddec8
--- /dev/null
+++ b/AcWing/4003/4003.cpp
@@ -0,0 +1,24 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int n, a[1005], f[1000005];
+
+int main() {
+    cin >> n;
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+    }
+    sort(a + 1, a + 1 + n);
+    for (int i = n; i > 0; i--) {
+        bool flag = false;
+        for (int j = -1000; j <= 1000; j++) {
+            flag = flag || a[i] == 1ll * j * j;
+        }
+        if (!flag) {
+            cout << a[i] << endl;
+            exit(0);
+        }
+    }
+    return 0;
+}