import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringJoiner;
import java.util.StringTokenizer;
import java.util.function.IntUnaryOperator;
import java.util.function.LongUnaryOperator;

class Main {
    static In in = new In();
    static Out out = new Out();
    static long mod = 1000000007;
    static long inf = 0xfffffffffffffffL;

    long[] fac, inv;
    void solve() {
        int n = in.nextInt();
        int k = in.nextInt();

        fac = new long[2 * n + 2];
        inv = new long[2 * n + 2];
        fac[0] = inv[0] = 1;
        for (int i = 1; i < 2 * n + 2; i++) {
            fac[i] = fac[i - 1] * i % mod;
            inv[i] = powAndMod(fac[i], mod - 2);
        }

        if (n <= k) {
            out.println(comb(n + n - 1, n));
        } else {
            long ans = 0;
            for (int i = 0; i <= k; i++) {
                ans = (ans + comb(n, i) * comb(n - 1, i) % mod) % mod;
            }
            out.println(ans);
        }
    }

    long comb(int n, int r) {
        return fac[n] * inv[r] % mod * inv[n - r] % mod;
    }

    static long powAndMod(long a, long b) {
        long x = 1;
        while (b > 0) {
            if (b % 2 == 1) {
                x = x * a % mod;
                b--;
            } else {
                a = a * a % mod;
                b /= 2;
            }
        }
        return x;
    }

    public static void main(String[]$) {
        new Main().solve();
        out.flush();
    }
}

class In {
    private BufferedReader reader = new BufferedReader(new InputStreamReader(System.in), 0x10000);
    private StringTokenizer tokenizer;

    String next() {
        try {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                tokenizer = new StringTokenizer(reader.readLine());
            }
        } catch (IOException ignored) {
        }
        return tokenizer.nextToken();
    }

    int nextInt() {
        return Integer.parseInt(next());
    }

    long nextLong() {
        return Long.parseLong(next());
    }

    char[][] nextCharArray(int n, int m) {
        char[][] a = new char[n][m];
        for (int i = 0; i < n; i++) {
            a[i] = next().toCharArray();
        }
        return a;
    }

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

    int[] nextIntArray(int n, IntUnaryOperator op) {
        int[] a = new int[n];
        for (int i = 0; i < n; i++) {
            a[i] = op.applyAsInt(nextInt());
        }
        return a;
    }

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

    long[] nextLongArray(int n, LongUnaryOperator op) {
        long[] a = new long[n];
        for (int i = 0; i < n; i++) {
            a[i] = op.applyAsLong(nextLong());
        }
        return a;
    }
}

class Out {
    private static PrintWriter out = new PrintWriter(System.out);

    void println(Object... a) {
        StringJoiner joiner = new StringJoiner(" ");
        for (Object obj : a) {
            joiner.add(String.valueOf(obj));
        }
        out.println(joiner);
    }

    void flush() {
        out.flush();
    }
}


Measured memory_bytes: 27732