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 String S;
	//static String T;
	static long fac [];
	static int n;

	static final int mod = 1_000_000_007;
	//static LinkedList <Integer> adj []; 
	
	public static void main(String[] args) {
		n = sc.nextInt();
		int k = sc.nextInt();
		
		if (n-1<=k) {
			fac = new long [2*n+1];
			fac[0]=1;
			build_fac(2*n);
			
			out.println(nCr(2*n-1, n));
		}
		
		else {
			fac = new long [n+1];
			fac[0]=1;
			build_fac(n);
			
			long ans = 0;
			for (int i=0; i<=k; i++) 
				ans += nCr (n, i) * nCr(n-1, i) %mod;
			
			out.println(ans%mod);
		}
		
		out.flush();
	}
	
	public static long pow (long a, int j) {
	    long res=1;
	    while (j>0) {
	        if ((j-j/2*2)==1) {
	            res=(res*a)%mod;
	        }
	        a=(a*a)%mod;
	        j>>=1;
	    }
	    return res;
	}
	
	static void build_fac(int j) {
		long tmp = 1;
		for (int i=1; i<=j; i++) {
			tmp = (tmp*i)%mod;
			fac[i] = tmp;
		}
	}
 
	public static long modinv(long j) {
		return pow(j, mod-2);
	}
 
	public static long nCr(int j, int r) {
		return (fac[j] * modinv(fac[j-r]) % mod * modinv(fac[r]))%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 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 double nextDouble(){
		    	return Double.parseDouble(next());
		    }

		    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;
		      }
		    }
		  }

		}	 





Measured memory_bytes: 23252