#include <stdio.h>
#include <stdint.h>
#include <assert.h>
#include <string.h>

int ri() {
	int n;
	scanf("%d", &n);
	return n;
}
#define MOD 1000000007
int main() {
	int a, b, n;
	scanf("%d%d%d", &a, &b, &n);
	assert(0 <= a && a < MOD);
	assert(0 <= b && b < MOD);
	assert(0 <= n && n < MOD);
	int x[2][2] = {{0, 1}, {b, a}};
	int v[2] = {0, 1};
	for (; n; n >>= 1) {
		if (n & 1) {
			int t1 = ((int64_t) v[0] * x[0][0] + (int64_t) v[1] * x[0][1]) % MOD;
			int t2 = ((int64_t) v[0] * x[1][0] + (int64_t) v[1] * x[1][1]) % MOD;
			v[0] = t1, v[1] = t2;
		}
		int new_x[2][2];
		for (int i = 0; i < 2; i++)
			for (int j = 0; j < 2; j++) new_x[i][j] = ((int64_t) x[i][0] * x[0][j] + (int64_t) x[i][1] * x[1][j]) % MOD;
		memcpy(x, new_x, sizeof(new_x));
	}
	printf("%d\n", v[0]);
	return 0;
}