Given is an integer S. Find how many sequences there are whose terms are all integers greater than or equal to 3, and whose sum is equal to S. The answer can be very large, so output it modulo 10^9 + 7.

Constraints

* 1 \leq S \leq 2000
* All values in input are integers.

Input

Input is given from Standard Input in the following format:


S


Output

Print the answer.

Examples

Input

7


Output

3


Input

2


Output

0


Input

1729


Output

294867501
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;

import java.util.NoSuchElementException;

public class Main{
	static FastScanner sc = new FastScanner();
	static PrintWriter out = new PrintWriter(System.out);
	static int n;
	static int mod = 1_000_000_007;
	//static HashMap <String, Integer> map;
	
	public static void main(String[] args) {
		n = sc.nextInt();
		
		int lim = n/3;
		
		if (n<3)
			out.println(0);
		
		else {
			long ans = 0;
			for (int i=1; i<=lim; i++) {
				int l = n-i*3;
				ans+=nCr(i+l-1, i-1);
				ans%=mod;
			}
			
			out.println(ans);
		}
		 
		
		out.flush();
		
	}
	
	
	public static long factorial(int j, int lim) {
		long tmp = 1;
		for (int i=j; i>lim; i--) {
			tmp = (tmp*i)%mod;
		}
		return tmp;
	}
	
	public static long pow (long a, long j) {
	    long res=1;
	    
	    if (a==0)
	    	return 0;
	    
	    if (a==1)
	    	return 1;
	    
	    while (j>0) {
	        if ((j-j/2*2)==1) {
	            res=(res*a)%mod;
	        }
	        a=(a*a)%mod;
	        j>>=1;
	    }
	    return res;
	}
 
	public static long modinv(long j) {
		return pow(j, mod-2);
	}
 
	public static long nCr(int j, int r) {
		int lim = Math.max(j-r, r);
		int min = Math.min(j-r, r);
		
		return factorial(j, lim) * modinv(factorial(min, 0)) % mod ;
	}
	
	
	static class FastScanner {
	    private final InputStream in = System.in;
	    private final byte[] buffer = new byte[1024];
	    private int ptr = 0;
	    private int buflen = 0;

	    private boolean hasNextByte() {
	      if (ptr < buflen) {
	        return true;
	      } else {
	        ptr = 0;
	        try {
	          buflen = in.read(buffer);
	        } catch (IOException e) {
	          e.printStackTrace();
	        }
	        if (buflen <= 0) {
	          return false;
	        }
	      }
	      return true;
	    }

	    private int readByte() {
	      if (hasNextByte()) return buffer[ptr++];
	      else return -1;
	    }

	    private static boolean isPrintableChar(int c) {
	      return 33 <= c && c <= 126;
	    }

	    private void skipUnprintable() {
	      while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
	    }

	    public boolean hasNext() {
	      skipUnprintable();
	      return hasNextByte();
	    }

	    public String next() {
	      if (!hasNext()) throw new NoSuchElementException();
	      StringBuilder sb = new StringBuilder();
	      int b = readByte();
	      while (isPrintableChar(b)) {
	        sb.appendCodePoint(b);
	        b = readByte();
	      }
	      return sb.toString();
	    }
	    
	    public double nextDouble () {
	    	return Double.parseDouble(next());
	    }

	    public long nextLong() {
	      if (!hasNext()) throw new NoSuchElementException();
	      long n = 0;
	      boolean minus = false;
	      int b = readByte();
	      if (b == '-') {
	        minus = true;
	        b = readByte();
	      }
	      if (b < '0' || '9' < b) {
	        throw new NumberFormatException();
	      }
	      while (true) {
	        if ('0' <= b && b <= '9') {
	          n *= 10;
	          n += b - '0';
	        } else if (b == -1 || !isPrintableChar(b)) {
	          return minus ? -n : n;
	        } else {
	          throw new NumberFormatException();
	        }
	        b = readByte();
	      }
	    }

	    public int nextInt() {
	      return (int) nextLong();
	    }

	    public int[] nextIntArray(int N, boolean oneBased) {
	      if (oneBased) {
	        int[] array = new int[N + 1];
	        for (int i = 1; i <= N; i++) {
	          array[i] = sc.nextInt();
	        }
	        return array;
	      } else {
	        int[] array = new int[N];
	        for (int i = 0; i < N; i++) {
	          array[i] = sc.nextInt();
	        }
	        return array;
	      }
	    }

	    public long[] nextLongArray(int N, boolean oneBased) {
	      if (oneBased) {
	        long[] array = new long[N + 1];
	        for (int i = 1; i <= N; i++) {
	          array[i] = sc.nextLong();
	        }
	        return array;
	      } else {
	        long[] array = new long[N];
	        for (int i = 0; i < N; i++) {
	          array[i] = sc.nextLong();
	        }
	        return array;
	      }
	    }
	    
	    public double [] nextDoubleArray(int N, boolean oneBased) {
		      if (oneBased) {
		        double [] array = new double[N + 1];
		        for (int i = 1; i <= N; i++) {
		          array[i] = sc.nextDouble();
		        }
		        return array;
		      } else {
		        double[] array = new double[N];
		        for (int i = 0; i < N; i++) {
		          array[i] = sc.nextDouble();
		        }
		        return array;
		      }
		    }
		  
	  }
	
	
}
