Problem: There are r red and g green blocks for construction of the red-green tower. Red-green tower can be built following next rules:

  * Red-green tower is consisting of some number of levels;

  * Let the red-green tower consist of n levels, then the first level of this tower should consist of n blocks, second level — of n - 1 blocks, the third one — of n - 2 blocks, and so on — the last level of such tower should consist of the one block. In other words, each successive level should contain one block less than the previous one;

  * Each level of the red-green tower should contain blocks of the same color.

<image>

Let h be the maximum possible number of levels of red-green tower, that can be built out of r red and g green blocks meeting the rules above. The task is to determine how many different red-green towers having h levels can be built out of the available blocks.

Two red-green towers are considered different if there exists some level, that consists of red blocks in the one tower and consists of green blocks in the other tower.

You are to write a program that will find the number of different red-green towers of height h modulo 109 + 7.

Input

The only line of input contains two integers r and g, separated by a single space — the number of available red and green blocks respectively (0 ≤ r, g ≤ 2·105, r + g ≥ 1).

Output

Output the only integer — the number of different possible red-green towers of height h modulo 109 + 7.

Examples

Input

4 6


Output

2


Input

9 7


Output

6


Input

1 1


Output

2

Note

The image in the problem statement shows all possible red-green towers for the first sample.

Solution (in JAVA):

Solution:
/**
 * DA-IICT
 * Author : PARTH PATEL
 */
import java.io.*;
import java.math.*;
import java.util.*;
import java.util.logging.Level;

import static java.util.Arrays.fill;
import static java.lang.Math.*;
import static java.util.Arrays.sort;
import static java.util.Collections.sort;


public class D478 {

	public static int mod = 1000000007;
	//public static long INF = (1L << 60);
	static FasterScanner in = new FasterScanner();
	static PrintWriter out = new PrintWriter(System.out);
	public static int getmaxheight(int x)
	{
		int h=0;
		while(((h+1)*(h+2))/2<=(x))
			h++;
		return h;
	}
	public static void main(String[] args) {

		int r=in.nextInt();
		int g=in.nextInt();
		int maxheight=getmaxheight(r+g);
		int[][] dp=new int[2][r+1];
		//dp[i][j] is number of ways to make tower of height h with j red blocks
		//our answer will be dp[maxheight][r]
		dp[0][0]=1;
		for(int i=1;i<=maxheight;i++)
		{
			//2 choices 
			//1---> to use red for this height
			//2---> to use green for this height
			for(int red=0;red<=r;red++)
			{
				dp[i&1][red]=0;
				if(red-i>=0)
				dp[i&1][red]+=dp[(i^1)&1][red-i];   //used red
				int remgreen=g-((i*(i+1))/2-red);
				if(remgreen>=0)
				dp[i&1][red]+=dp[(i^1)&1][red];  //used green
				dp[i&1][red]%=mod;
			}
		}
		long answer=0;
		for(int i=0;i<=r;i++)
			{
			answer+=dp[maxheight&1][i];
			}
		out.println(answer%mod);
		out.close();

	}

	public static long pow(long x, long n, long mod) {
		long res = 1;
		for (long p = x; n > 0; n >>= 1, p = (p * p) % mod) {
			if ((n & 1) != 0) {
				res = (res * p % mod);
			}
		}
		return res;
	}

	public static long gcd(long n1, long n2) {
		long r;
		while (n2 != 0) {
			r = n1 % n2;
			n1 = n2;
			n2 = r;
		}
		return n1;
	}

	public static long lcm(long n1, long n2) {
		long answer = (n1 * n2) / (gcd(n1, n2));
		return answer;
	}

	static class FasterScanner {
		private byte[] buf = new byte[1024];
		private int curChar;
		private int snumChars;

		public int read() {
			if (snumChars == -1)
				throw new InputMismatchException();
			if (curChar >= snumChars) {
				curChar = 0;
				try {
					snumChars = System.in.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (snumChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public String nextLine() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndOfLine(c));
			return res.toString();
		}

		public String nextString() {
			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 long nextLong() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long 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 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 - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public int[] nextIntArray(int n) {
			int[] arr = new int[n];
			for (int i = 0; i < n; i++) {
				arr[i] = nextInt();
			}
			return arr;
		}

		public long[] nextLongArray(int n) {
			long[] arr = new long[n];
			for (int i = 0; i < n; i++) {
				arr[i] = nextLong();
			}
			return arr;
		}

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

		private boolean isEndOfLine(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}
	}

}