use std::array;

use proconio::{fastout, input};
const M: usize = 1000000007;

#[fastout]
fn main() {
    input! {
        a: usize, b: usize, n: usize,
    }
    let mat = [[0, 1], [b, a]];
    let mut doubling = mat;
    let mut acc = [[1, 0], [0, 1]];
    for i in 0..64 - n.leading_zeros() {
        if n >> i & 1 == 1 {
            acc = mat_mul(&acc, &doubling);
        }
        doubling = mat_mul(&doubling, &doubling);
    }
    println!("{}", acc[0][1]);
}

fn mat_mul(l: &[[usize; 2]; 2], r: &[[usize; 2]; 2]) -> [[usize; 2]; 2] {
    array::from_fn(|i| array::from_fn(|j| (l[i][0] * r[0][j] % M + l[i][1] * r[1][j] % M) % M))
}