From afbe224a1280953a9224d183b2749975460ef795 Mon Sep 17 00:00:00 2001
From: Jihoon Lee <hiyabye0465@gmail.com>
Date: Tue, 26 Mar 2024 23:17:41 +0900
Subject: [PATCH] Add 01813.cpp

---
 01xxx/01813.cpp | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 01xxx/01813.cpp

diff --git a/01xxx/01813.cpp b/01xxx/01813.cpp
new file mode 100644
index 00000000..fc956861
--- /dev/null
+++ b/01xxx/01813.cpp
@@ -0,0 +1,26 @@
+#include <iostream>
+#include <vector>
+using namespace std;
+
+int solve(void) {
+  int n; cin >> n;
+
+  vector<int> ans(n+1, 0);
+  for (int i=0; i<n; i++) {
+    int x; cin >> x;
+    ans[x]++;
+  }
+
+  for (int i=n; i>=0; i--) {
+    if (ans[i] == i) return i;
+  }
+  return -1;
+}
+
+int main(void) {
+  ios::sync_with_stdio(false);
+  cin.tie(nullptr);
+
+  cout << solve();
+  return 0;
+}
\ No newline at end of file