#include<bits/stdc++.h>
using namespace std;
#define fs first
#define sc second
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define ALL(A) A.begin(),A.end()
#define RALL(A) A.rbegin(),A.rend()
typedef long long LL;
typedef pair<int,int> P;
const LL mod=1000000007;
const LL LINF=1LL<<60;
const int INF=1<<30;



typedef vector<vector<LL>> mat;

mat mul(mat A,mat B){
    mat C(A.size(),vector<LL> (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++){
                C[i][j]=(C[i][j]+A[i][k]*B[k][j])%mod;
            }
        }
    }
    return C;
}

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



int main(){
    LL a,b,n;cin >> a >> b >> n;
    if(n==0){
        puts("0");
        return 0;
    }
    mat h(2,vector<LL>(2,0));
    h[0][0] = a;
    h[0][1] = b;
    h[1][0] = 1;
    auto H = pow(h,n-1);
    mat s(2,vector<LL> (1,0));
    s[1][0] = 0;
    s[0][0] = 1;
    auto p = mul(H,s);
    cout << p[0][0] << endl;
    return 0;
}