#include <iostream>

using namespace std;

typedef long long ll;
const ll MOD = 1000000007;

void prod(ll a[2][2], ll b[2][2], ll ans[2][2]){
    for(int i = 0; i < 2; i++){
        for(int j = 0; j < 2; j++){
            ans[i][j] = 0;
            for(int k = 0; k < 2; k++){
                ans[i][j] += a[i][k]*b[k][j];
                ans[i][j] %= MOD;
            }
        }
    }
}

void copy(ll a[2][2], ll b[2][2]){
    for(int i = 0; i < 2; i++){
        for(int j = 0; j < 2; j++){
            b[i][j] = a[i][j];
        }
    }
}

void pow(ll a[2][2], ll n, ll ans[2][2]){
    ll buf[2][2];
    ll tmp[2][2];
    copy(a, tmp);

    ans[0][0] = 1; ans[1][1] = 1;
    ans[0][1] = 0; ans[1][0] = 0;
    for(int i = 0; i <= 30; i++){
        ll m = (ll)1 << i;
        if(m&n){
            prod(tmp, ans, buf);
            copy(buf, ans);
        }
        prod(tmp, tmp, buf);
        copy(buf, tmp);
    }
}

int main(){
    ll a, b, n;
    cin >> a >> b >> n;
    ll s[2][2];
    ll ans[2][2];
    s[0][0] = a;
    s[0][1] = b;
    s[1][0] = 1;
    s[1][1] = 0;
    pow(s, n, ans);
    cout << ans[1][0] << endl;
}