F.java

import java.io.IOException;
import java.io.InputStream;

public class F {
    public static void main(String[] args) throws Exception {
        FastScanner fs = new FastScanner(System.in);
        Integer nObj = fs.nextIntNullable();
        if (nObj == null) {
            return;
        }
        int n = nObj;
        int[] a = new int[n];
        for (int i = 0; i < n; i++) {
            Integer v = fs.nextIntNullable();
            if (v == null) {
                return;
            }
            a[i] = v;
        }

        int left = 1, right = n, answer = 0;
        while (left <= right) {
            int mid = left + (right - left) / 2;
            if (existsBeautiful(a, mid)) {
                answer = mid;
                left = mid + 1;
            } else {
                right = mid - 1;
            }
        }

        System.out.println(answer);
    }

    static boolean existsBeautiful(int[] a, int k) {
        int consecutive = 0;
        for (int val : a) {
            if (val >= k) {
                consecutive++;
                if (consecutive >= k) return true;
            } else {
                consecutive = 0;
            }
        }
        return false;
    }

    static class FastScanner {
        private final InputStream in;
        private final byte[] buffer = new byte[1 << 16];
        private int ptr = 0, len = 0;

        FastScanner(InputStream is) { this.in = is; }

        private int read() throws IOException {
            if (ptr >= len) {
                len = in.read(buffer);
                ptr = 0;
                if (len <= 0) return -1;
            }
            return buffer[ptr++];
        }

        Integer nextIntNullable() throws IOException {
            int c;
            do {
                c = read();
                if (c == -1) return null;
            } while (c <= ' ');
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            int val = 0;
            while (c > ' ') {
                if (c < '0' || c > '9') {
                    while (c > ' ') c = read();
                    break;
                }
                val = val * 10 + (c - '0');
                c = read();
            }
            return val * sgn;
        }
    }
}