#include <bits/stdc++.h>

#include <atcoder/modint>

#include <atcoder/modint>
#include <vector>

template <class T>
struct Factorial {
    int n;
    std::vector<T> fact;
    std::vector<T> revfact;

    Factorial(int n) : n(n) {
        fact.resize(n + 1);
        revfact.resize(n + 1);
        fact[0] = 1;
        for (int i = 0; i < n; ++i) fact[i + 1] = fact[i] * (i + 1);

        revfact[n] = fact[n].inv();
        for (int i = n - 1; i >= 0; --i) revfact[i] = revfact[i + 1] * (i + 1);
    }

    T comb(int n, int r) {
        if (n < r || r < 0) return 0;
        return fact[n] * revfact[r] * revfact[n - r];
    }

    T perm(int n, int r) {
        if (n < r || r < 0) return 0;
        return fact[n] * revfact[n - r];
    }
};


#include <algorithm>
#include <cassert>
#include <vector>

template <class T>
bool chmax(T &a, const T &b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

template <class T>
bool chmin(T &a, const T &b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

template <class T>
T div_floor(T a, T b) {
    if (b < 0) a *= -1, b *= -1;
    return a >= 0 ? a / b : (a + 1) / b - 1;
}

template <class T>
T div_ceil(T a, T b) {
    if (b < 0) a *= -1, b *= -1;
    return a > 0 ? (a - 1) / b + 1 : a / b;
}

template <typename T>
struct CoordComp {
    std::vector<T> v;
    bool sorted;

    CoordComp() : sorted(false) {}

    int size() { return v.size(); }

    void add(T x) { v.push_back(x); }

    void build() {
        std::sort(v.begin(), v.end());

        v.erase(std::unique(v.begin(), v.end()), v.end());
        sorted = true;
    }

    int get_idx(T x) {
        assert(sorted);
        return lower_bound(v.begin(), v.end(), x) - v.begin();
    }

    T &operator[](int i) { return v[i]; }
};


#define For(i, a, b) for (int i = (int)(a); (i) < (int)(b); ++(i))
#define rFor(i, a, b) for (int i = (int)(a)-1; (i) >= (int)(b); --(i))
#define rep(i, n) For(i, 0, n)
#define rrep(i, n) rFor(i, n, 0)
#define fi first
#define se second

using namespace std;

using lint = long long;
using pii = pair<int, int>;
using pll = pair<lint, lint>;

using mint = atcoder::modint1000000007;

int main() {
    int n, K;
    scanf("%d%d", &n, &K);

    Factorial<mint> fc(n);
    mint ans = 0;
    mint C = K;
    For(k, 1, min(K + 1, n + 1)) {
        ans += C * fc.comb(n - 1, k - 1) * mint(2).pow(k - 1);
        C *= mint(K - k) / mint(k + 1);
    }
    printf("%u\n", ans.val());
}