#include<bits/stdc++.h>
#define int long long
using namespace std;

const int mod=1e9+7;

template<class T>
struct Matrix
{
    vector<vector<T>> A;
    Matrix(){}
    Matrix(int n,int m):A(n,vector<T>(m,0)){}
    Matrix(int n):A(n,vector<T>(n,0)){};
    int height() const{
        return (A.size());
    }
    int width() const{
        return (A[0].size());
    }
    inline const vector<T> &operator[](int k) const{
        return (A.at(k));
    }
    inline vector<T> &operator[](int k){
        return (A.at(k));
    }
    static Matrix I(int n){
        Matrix mat(n);
        for(int i=0;i<n;i++) mat[i][i]=1;
        return (mat);
    }
    Matrix &operator+=(const Matrix &B){
        int n=height(), m=width();
        assert(n==B.height() && m==B.width());
        for(int i=0;i<n;i++) for(int j=0;j<m;j++){
            (*this)[i][j]+=B[i][j];
        }
        return (*this);
    }
    Matrix &operator-=(const Matrix &B){
        int n=height(), m=width();
        assert(n==B.height() && m==B.width());
        for(int i=0;i<n;i++) for(int j=0;j<m;j++){
            (*this)[i][j]-=B[i][j];
        }
        return (*this);
    }
    Matrix &operator*=(const Matrix &B){
        int n=height(), m=B.width(), p=width();
        assert(p==B.height());
        vector<vector<T>> C(n,vector<T>(m,0));
        for(int i=0;i<n;i++) for(int j=0;j<m;j++){
            for(int k=0;k<p;k++){
                C[i][j]=(C[i][j]+(*this)[i][k]*B[k][j]);
                C[i][j]%=mod;
            }
        }
        A.swap(C);
        return (*this);
    }
    Matrix &operator^=(int k){
        Matrix B=Matrix::I(height());
        while(k>0){
            if(k&1) B*=*this;
            *this*=*this;
            k>>=1;
        }
        A.swap(B.A);
        return (*this);
    }
    Matrix operator+(const Matrix &B) const{
        return (Matrix(*this)+=B);
    }
    Matrix operator-(const Matrix &B) const{
        return (Matrix(*this)-=B);
    }
    Matrix operator*(const Matrix &B) const{
        return (Matrix(*this)*=B);
    }
    Matrix operator^(const int k) const{
        return (Matrix(*this)^=k);
    }
};

signed main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);

    int a,b,n; cin>>a>>b>>n;
    Matrix<int> A(2);
    A[0][0]=a; A[0][1]=b;
    A[1][0]=1; A[1][1]=0;
    A^=n;
    cout<<A[1][0]<<endl;
    return 0;
}