#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<vector>
#include<string>
#include<utility>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<functional>
#include<math.h>
#include<random>
#include <bitset>
using namespace std;
#define N (1000000000+7)
//#define N 998244353
#define INF 1e16
typedef long long ll;
typedef pair<int,int> P;
typedef vector<ll> vec;
typedef vector<vec> mat;
 
const int inf = (int)1e9; 

mat  mul(mat &A,mat &B){
    mat C(A.size(),vec(B[0].size()));
    for(int i=0;i<A.size();i++){
        for(int k=0;k<B.size();k++){
            for(int j=0;j<B[0].size();j++){
                ll t = (A[i][k]*B[k][j])%N;
                C[i][j] = (C[i][j]+t)%N;
                C[i][j] = (C[i][j]+N)%N;
            }
        }
    }
    return C;
}

mat Pow(mat A,ll n){
    mat B(A.size(),vec(A.size()));
    for(int i=0;i<A.size();i++)B[i][i]=1LL;
    while(n>0){
        if(n&1)B = mul(B,A);
        A = mul(A,A);
        n>>=1;
    }
    return B;
}

int main(void){
    ll a,b,n;
    cin>>a>>b>>n;
    mat A(2,vec(2));
    A[0][0]=a;
    A[0][1]=b;
    A[1][0]=1;
    A[1][1]=0;
    A = Pow(A,n);
    cout<<A[1][0]<<endl;
    return 0;
}