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// Problem: Od deski do deski [A]
// https://sio2.mimuw.edu.pl/c/pa-2021-1/p/odd/

#include <cstdio>
#include <cmath>
#include <iostream>
#include <algorithm>
#include <string>
#include <cctype>
#include <vector>
#include <set>
#include <map>
using namespace std;
#define REP(i,n) for(int _n=(n), i=0;i<_n;++i)
#define FOR(i,a,b) for(int i=(a),_b=(b);i<=_b;++i)
#define FORD(i,a,b) for(int i=(a),_b=(b);i>=_b;--i)
#define FOREACH(e, v) for(auto const &e: v)
#define IN(e, s) (s).find((e)) != (s).end()
#define TRACE(x) cerr << "TRACE(" #x ")" << endl;
#define DEBUG(x) cerr << #x << " = " << (x) << endl;
#define PB push_back
#define ST first
#define ND second
#define ALL(c) (c).begin(), (c).end()
#define SZ(x) ((int)(x).size())
typedef long long LL; typedef unsigned long long ULL; typedef unsigned short UST; typedef unsigned int UINT;
typedef vector<int> VI;
inline  void fix_io() { cin.tie(nullptr); ios::sync_with_stdio(false); }

const double p = 1000000007;

ULL power(ULL x, int y, int p) {
    ULL res=1;
    x = x % p;
    while (y > 0) {
        if (y & 1) res = (res * x) % p;
        y = y >> 1; // y = y/2
        x = (x * x) % p;
    }
    return res;
}

int main() {
    fix_io();
    UST n;
    UINT m;
    ULL ans = 0;
    cin >> n >> m;
    FOR (i, 1, n-1) {
        ans += power(m,n-i,p);
    }
    ans -= 2*m;
    cout << ans << '\n';
}