Problem:
Score : 500 points

Problem Statement

You are given a sequence (P_1,P_2,...,P_N) which is a permutation of the integers from 1 through N.
You would like to sort this sequence in ascending order by repeating the following operation:

Choose an element in the sequence and move it to the beginning or the end of the sequence.

Find the minimum number of operations required.
It can be proved that it is actually possible to sort the sequence using this operation.

Constraints

1 \leq N \leq 2\times 10^5

(P_1,P_2,...,P_N) is a permutation of (1,2,...,N).

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
P_1
:
P_N

Output

Print the minimum number of operations required.

Sample Input 1

4
1
3
2
4

Sample Output 1

2

For example, the sequence can be sorted in ascending order as follows:

Move 2 to the beginning. The sequence is now (2,1,3,4).

Move 1 to the beginning. The sequence is now (1,2,3,4).

Sample Input 2

6
3
2
5
1
4
6

Sample Output 2

4

Sample Input 3

8
6
3
1
2
7
4
8
5

Sample Output 3

5

Solution in C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Net.Mail;

namespace Contest
{
    class Scanner
    {
        private string[] line = new string[0];
        private int index = 0;
        public string Next()
        {
            if (line.Length <= index)
            {
                line = Console.ReadLine().Split(' ');
                index = 0;
            }
            var res = line[index];
            index++;
            return res;
        }
        public int NextInt()
        {
            return int.Parse(Next());
        }
        public long NextLong()
        {
            return long.Parse(Next());
        }
        public string[] Array()
        {
            line = Console.ReadLine().Split(' ');
            index = line.Length;
            return line;
        }
        public int[] IntArray()
        {
            var array = Array();
            var result = new int[array.Length];
            for (int i = 0; i < array.Length; i++)
            {
                result[i] = int.Parse(array[i]);
            }

            return result;
        }
        public long[] LongArray()
        {
            var array = Array();
            var result = new long[array.Length];
            for (int i = 0; i < array.Length; i++)
            {
                result[i] = long.Parse(array[i]);
            }

            return result;
        }
    }

    class SegTree<T>
    {
        private readonly T[] Array;
        private readonly Comparison<T> Compare;
        private readonly int N;
        private readonly T Max;
        public SegTree(int size, T max) : this(size, Comparer<T>.Default, max) { }
        public SegTree(int size, IComparer<T> comparer, T max) : this(size, comparer.Compare, max) { }
        public SegTree(int size, Comparison<T> comparison, T max)
        {
            Max = max;
            N = 1;
            while (N < size)
            {
                N *= 2;
            }
            Compare = comparison;
            Array = new T[2 * N];
            for (int i = 1; i < 2 * N; i++)
            {
                Array[i] = max;
            }
        }

        new public T this[int i]
        {
            get { return Array[i + N]; }
            set { Update(value, i); }
        }


        private T Min(T x, T y)
        {
            return Compare(x, y) < 0 ? x : y;
        }

        public void Update(T item, int index)
        {
            index += N;
            Array[index] = item;
            while (index > 1)
            {
                index /= 2;
                Array[index] = Min(Array[index * 2], Array[index * 2 + 1]);
            }
        }

        private T Q(int left, int right, int k, int l, int r)
        {
            if (left <= l && r <= right)
            {
                return Array[k];
            }
            if (r <= left || right <= l)
            {
                return Max;
            }
            return Min(Q(left, right, k * 2, l, (l + r) / 2), Q(left, right, k * 2 + 1, (l + r) / 2, r));
        }

        public T Query(int left, int right)
        {
            return Q(left, right, 1, 0, N);
        }

    }

    class Program
    {
        private int N;
        private int[] P;
        public void Solve()
        {
            var sc = new Scanner();
            N = sc.NextInt();
            P = new int[N];
            for (int i = 0; i < N; i++)
            {
                P[i] = sc.NextInt();
            }
            var segtree = new SegTree<int>(N + 1, (a, b) => -a.CompareTo(b), 0);
            foreach (int i in P)
            {
                segtree[i] = segtree.Query(1, i) + 1;
            }
            Console.WriteLine(N - segtree.Query(1, N + 1) + 1);
        }

        static void Main(string[] args)
        {
            new Program().Solve();
        }
    }
}