diff --git a/problem/P3853/P3853.cpp b/problem/P3853/P3853.cpp
new file mode 100644
index 00000000..70b2adca
--- /dev/null
+++ b/problem/P3853/P3853.cpp
@@ -0,0 +1,30 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int l, r, n, k, a[100005];
+
+bool check(int mid) {
+    int m = 0;
+    for (int i = 2; i <= n; i++) {
+        if (a[i] - a[i - 1] >= mid) {
+            m += (a[i] - a[i - 1]) / mid;
+            if ((a[i] - a[i - 1]) % mid == 0) m--;
+        }
+    }
+    return m <= k;
+}
+
+int main() {
+    cin >> r >> n >> k;
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+    }
+    while (l < r) {
+        int mid = l + r >> 1;
+        if (check(mid)) r = mid;
+        else l = mid + 1;
+    }
+    cout << l << endl;
+    return 0;
+}