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
import java.io.OutputStreamWriter;
import java.io.BufferedWriter;
import java.util.Comparator;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Random;
import java.io.Writer;
import java.util.HashSet;
import java.util.List;
import java.io.IOException;
import java.util.Arrays;
import java.util.InputMismatchException;
import java.util.ArrayList;
import java.util.NoSuchElementException;
import java.util.TreeSet;
import java.math.BigInteger;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 * @author Alex
 */
public class Main {
	public static void main(String[] args) {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		InputReader in = new InputReader(inputStream);
		OutputWriter out = new OutputWriter(outputStream);
		TaskB solver = new TaskB();
		solver.solve(1, in, out);
		out.close();
	}
}

class TaskB {
    public void solve(int testNumber, InputReader in, OutputWriter out){
	    int n = in.ri();
	    IntPair[] items = new IntPair[n];
	    for(int i = 0; i < n; i++) items[i] = new IntPair(in.ri(), in.ri());
	    long[][] mem = new long[n][4011];
	    ArrayUtils.fill(mem, -1);
	    long res = dp(0, 0, items, mem);
	    out.printLine(res);
    }
	long dp(int index, int timebank, IntPair[] items, long[][] mem){
		if (index == items.length && timebank < 0) return (long) 1e15;
		if (index == items.length) return 0;
		if (timebank >= 2004) timebank = 2004;
		if (mem[index][timebank +  2004] != -1) return mem[index][timebank + 2004];
		long steal = dp(index + 1, timebank - 1, items, mem);
		long dont = dp(index + 1, timebank + items[index].first, items, mem) + items[index].second;
		return mem[index][timebank + 2004] = Math.min(steal, dont);
	}
}

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

	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 ri(){
		return readInt();
	}

	public int readInt() {
		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 - '0';
			c = read();
		} while (!isSpaceChar(c));
		return res * sgn;
	}
	public boolean isSpaceChar(int c) {
		if (filter != null)
			return filter.isSpaceChar(c);
		return isWhitespace(c);
	}

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

class OutputWriter {
	private final PrintWriter writer;

	public OutputWriter(OutputStream outputStream) {
		writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
	}
	public void close() {
		writer.close();
	}
	public void printLine(long i) {
		writer.println(i);
	}
}

class IntPair implements Comparable<IntPair> {
public int first, second;


	public IntPair(int first, int second) {
		this.first = first;
		this.second = second;
	}
	public String toString() {
		return "(" + first + "," + second + ")";
	}

	public boolean equals(Object o) {
		if (this == o) return true;
		if (o == null || getClass() != o.getClass()) return false;

		IntPair intPair = (IntPair) o;

		return first == intPair.first && second == intPair.second;

	}

	public int hashCode() {
		int result = first;
		result = 31 * result + second;
		return result;
	}

	public int compareTo(IntPair o) {
		if (first < o.first)
			return -1;
		if (first > o.first)
			return 1;
		if (second < o.second)
			return -1;
		if (second > o.second)
			return 1;
		return 0;
	}
}

class ArrayUtils {
	public static void fill(long[][] array, long value) {
		for (long[] row : array)
			Arrays.fill(row, value);
	}
}

