Bob came to a cash & carry store, put n items into his trolley, and went to the checkout counter to pay. Each item is described by its price ci and time ti in seconds that a checkout assistant spends on this item. While the checkout assistant is occupied with some item, Bob can steal some other items from his trolley. To steal one item Bob needs exactly 1 second. What is the minimum amount of money that Bob will have to pay to the checkout assistant? Remember, please, that it is Bob, who determines the order of items for the checkout assistant.

Input

The first input line contains number n (1 ≤ n ≤ 2000). In each of the following n lines each item is described by a pair of numbers ti, ci (0 ≤ ti ≤ 2000, 1 ≤ ci ≤ 109). If ti is 0, Bob won't be able to steal anything, while the checkout assistant is occupied with item i.

Output

Output one number — answer to the problem: what is the minimum amount of money that Bob will have to pay.

Examples

Input

4
2 10
0 20
1 5
1 3


Output

8


Input

3
0 1
0 10
0 100


Output

111
//package codeforces;

import java.io.*;
import java.util.*;

public final class CheckoutAssistant
{
    public static void main(String[] args)
    {
        InputReader in = new InputReader(System.in);
        OutputWriter out = new OutputWriter(System.out);
        Solver solver = new Solver(in, out);

        solver.solve();

        in.close();
        out.flush();
        out.close();
    }

    static class Solver
    {
        static final long INFINITY = (long) 1e15;
        int n;
        Item[] items;
        long[][] dp;
        InputReader in;
        OutputWriter out;

        void solve()
        {
            n = in.nextInt();
            items = new Item[n];

            long total = 0;

            for (int i = 0; i < n; i++)
            {
                items[i] = new Item(in.nextInt() + 1, in.nextInt());
                total += items[i].cost;
            }

            // dp[i][j] stores the minimum cost we have to pay for i items, which take j time

            dp = new long[n + 1][n + 1];

/*            Arrays.fill(dp[0], INFINITY);

            for (int i = 1; i <= n; i++)
                dp[i][0] = INFINITY;

            dp[0][0] = 0;*/

            for (int i = 0; i <= n; i++)
                Arrays.fill(dp[i], INFINITY);

            dp[0][0] = 0;

            for (int i = 1; i <= n; i++)
            {
                for (int j = 0; j <= n; j++)
                {
//                    if (items[i - 1].time > j)
//                        dp[i][j] = Math.min(dp[i][j], dp[i - 1][j]);
//                    else
                    {
                        int left = Math.max(0, j - items[i - 1].time);
                        dp[i][j] = Math.min(dp[i - 1][left] + items[i - 1].cost, dp[i - 1][j]);

                        int ind = Math.min(n, j + items[i - 1].time);
                        dp[i][ind] = Math.min(dp[i][ind], dp[i][j]);
                    }
                }
            }

/*            System.out.println("dp :");

            for (int i = 0; i <= n; i++, System.out.println())
                for (int j = 0; j <= n; j++)
                    System.out.print(dp[i][j] + " ");*/

            out.println(dp[n][n]);
        }

        long find(int index, int remainingTime)
        {
            if (index == n)
                return 0;

            if (dp[index][remainingTime] != INFINITY)
                return dp[index][remainingTime];

            if (remainingTime > 0)
                ;

            return 0;
        }

        class Item
        {
            int time, cost;

            public Item(int time, int cost)
            {
                this.time = time;
                this.cost = cost;
            }

        }

        public Solver(InputReader in, OutputWriter out)
        {
            this.in = in;
            this.out = out;
        }

    }

    static class InputReader
    {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;

        public InputReader(InputStream stream)
        {
            this.stream = stream;
        }

        public int read()
        {
            if (numChars == -1)
                throw new InputMismatchException();

            if (curChar >= numChars)
            {
                curChar = 0;
                try
                {
                    numChars = stream.read(buf);
                }
                catch (IOException e)
                {
                    throw new InputMismatchException();
                }
                if (numChars <= 0)
                    return -1;
            }

            return buf[curChar++];
        }

        public int nextInt()
        {
            int c = read();

            while (isSpaceChar(c))
                c = read();

            int sgn = 1;

            if (c == '-')
            {
                sgn = -1;
                c = read();
            }

            int res = 0;

            do
            {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();

                res *= 10;
                res += c & 15;

                c = read();
            } while (!isSpaceChar(c));

            return res * sgn;
        }

        public int[] nextIntArray(int arraySize)
        {
            int array[] = new int[arraySize];

            for (int i = 0; i < arraySize; i++)
                array[i] = nextInt();

            return array;
        }

        public long nextLong()
        {
            int c = read();

            while (isSpaceChar(c))
                c = read();

            int sign = 1;

            if (c == '-')
            {
                sign = -1;

                c = read();
            }

            long result = 0;

            do
            {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();

                result *= 10;
                result += c & 15;

                c = read();
            } while (!isSpaceChar(c));

            return result * sign;
        }

        public long[] nextLongArray(int arraySize)
        {
            long array[] = new long[arraySize];

            for (int i = 0; i < arraySize; i++)
                array[i] = nextLong();

            return array;
        }

        public float nextFloat() // problematic
        {
            float result, div;
            byte c;

            result = 0;
            div = 1;
            c = (byte) read();

            while (c <= ' ')
                c = (byte) read();

            boolean isNegative = (c == '-');

            if (isNegative)
                c = (byte) read();

            do
            {
                result = result * 10 + c - '0';
            } while ((c = (byte) read()) >= '0' && c <= '9');

            if (c == '.')
                while ((c = (byte) read()) >= '0' && c <= '9')
                    result += (c - '0') / (div *= 10);

            if (isNegative)
                return -result;

            return result;
        }

        public double nextDouble() // not completely accurate
        {
            double ret = 0, div = 1;
            byte c = (byte) read();

            while (c <= ' ')
                c = (byte) read();

            boolean neg = (c == '-');

            if (neg)
                c = (byte) read();

            do
            {
                ret = ret * 10 + c - '0';
            } while ((c = (byte) read()) >= '0' && c <= '9');

            if (c == '.')
                while ((c = (byte) read()) >= '0' && c <= '9')
                    ret += (c - '0') / (div *= 10);

            if (neg)
                return -ret;

            return ret;
        }

        public String next()
        {
            int c = read();

            while (isSpaceChar(c))
                c = read();

            StringBuilder res = new StringBuilder();

            do
            {
                res.appendCodePoint(c);

                c = read();
            } while (!isSpaceChar(c));

            return res.toString();
        }

        public boolean isSpaceChar(int c)
        {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public String nextLine()
        {
            int c = read();

            StringBuilder result = new StringBuilder();

            do
            {
                result.appendCodePoint(c);

                c = read();
            } while (!isNewLine(c));

            return result.toString();
        }

        public boolean isNewLine(int c)
        {
            return c == '\n';
        }

        public void close()
        {
            try
            {
                stream.close();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
        }

    }

    static class OutputWriter
    {
        private PrintWriter writer;

        public OutputWriter(OutputStream stream)
        {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(
                    stream)));
        }

        public OutputWriter(Writer writer)
        {
            this.writer = new PrintWriter(writer);
        }

        public void println(int x)
        {
            writer.println(x);
        }

        public void print(int x)
        {
            writer.print(x);
        }

        public void println(char x)
        {
            writer.println(x);
        }

        public void print(char x)
        {
            writer.print(x);
        }

        public void println(int array[], int size)
        {
            for (int i = 0; i < size; i++)
                println(array[i]);
        }

        public void print(int array[], int size)
        {
            for (int i = 0; i < size; i++)
                print(array[i] + " ");
        }

        public void println(long x)
        {
            writer.println(x);
        }

        public void print(long x)
        {
            writer.print(x);
        }

        public void println(long array[], int size)
        {
            for (int i = 0; i < size; i++)
                println(array[i]);
        }

        public void print(long array[], int size)
        {
            for (int i = 0; i < size; i++)
                print(array[i]);
        }

        public void println(float num)
        {
            writer.println(num);
        }

        public void print(float num)
        {
            writer.print(num);
        }

        public void println(double num)
        {
            writer.println(num);
        }

        public void print(double num)
        {
            writer.print(num);
        }

        public void println(String s)
        {
            writer.println(s);
        }

        public void print(String s)
        {
            writer.print(s);
        }

        public void println()
        {
            writer.println();
        }

        public void printSpace()
        {
            writer.print(" ");
        }

        public void printf(String format, Object args)
        {
            writer.printf(format, args);
        }

        public void flush()
        {
            writer.flush();
        }

        public void close()
        {
            writer.close();
        }

    }

    static class CMath
    {
        static long power(long number, long power)
        {
            if (number == 1 || number == 0 || power == 0)
                return 1;

            if (power == 1)
                return number;

            if (power % 2 == 0)
                return power(number * number, power / 2);
            else
                return power(number * number, power / 2) * number;
        }

        static long modPower(long number, long power, long mod)
        {
            if (number == 1 || number == 0 || power == 0)
                return 1;

            number = mod(number, mod);

            if (power == 1)
                return number;

            long square = mod(number * number, mod);

            if (power % 2 == 0)
                return modPower(square, power / 2, mod);
            else
                return mod(modPower(square, power / 2, mod) * number, mod);
        }

        static long moduloInverse(long number, long mod)
        {
            return modPower(number, mod - 2, mod);
        }

        static long mod(long number, long mod)
        {
            return number - (number / mod) * mod;
        }

        static int gcd(int a, int b)
        {
            if (b == 0)
                return a;
            else
                return gcd(b, a % b);
        }

    }

}

/*

4
2 10
0 20
1 5
1 3

 */
