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#include <iostream>
#include <vector>
#include <unordered_set>
using namespace std;

void addTree(vector<int>& currentTreeSequence, int numberOfTrees, int numberOfTreeSpecies, int currentLength) {
    if (currentLength == numberOfTrees) {
        //if (currentTreeSequence[0] != currentTreeSequence[currentTreeSequence.size() - 1]) {
            for (int i = 0; i < currentTreeSequence.size(); i++) {
                cout << currentTreeSequence[i] << "";
            }
            cout << endl;
        //}

        return;
    }

    for (int i = 0; i < numberOfTreeSpecies; i++) {
        currentTreeSequence[currentLength] = i;
        addTree(currentTreeSequence, numberOfTrees, numberOfTreeSpecies, currentLength + 1);
    }
}

void generateAllTreeSequences(int numberOfTrees, int numberOfTreeSpecies) {
    vector<int> currentTreeSequence(numberOfTrees);
    addTree(currentTreeSequence, numberOfTrees, numberOfTreeSpecies, 0);
}

bool isValidSequence(vector<int> currentTreeSequence) {
    return false;
}


int main() {
    std::ios::sync_with_stdio(false);

    int numberOfTrees, numberOfTreeSpecies;
    cin >> numberOfTrees >> numberOfTreeSpecies;
    //generateAllTreeSequences(numberOfTrees, numberOfTreeSpecies);

    if (numberOfTrees < 2) {
        cout << 0;
        return 0;
    }

    if (numberOfTrees < 4) {
        cout << numberOfTreeSpecies;
        return 0;
    }

    vector<long long int> numberOfPossibilites(numberOfTrees + 1, 0);

    if (numberOfTreeSpecies == 2) {
        numberOfPossibilites[2] = 2;
        numberOfPossibilites[3] = 4;

        for (int i = 4; i <= numberOfTrees; i++) {
            numberOfPossibilites[i] = (long long)(numberOfPossibilites[i - 1] * 2 + 2 * (i - 3)) % 1000000007;
        }

    } else if (numberOfTreeSpecies == 3) {
        numberOfPossibilites[2] = 3;
        numberOfPossibilites[3] = 9;

        for (int i = 4; i <= numberOfTrees; i++) {
            numberOfPossibilites[i] = (long long)(numberOfPossibilites[i - 1] * 3 + 9) % 1000000007;
        }
    } else {
        numberOfPossibilites[numberOfTrees] = -1;
    }

    cout << numberOfPossibilites[numberOfTrees];
}