MOD = 10**9 + 7

def matrix_mult(a, b):
    res = [[0] * 2 for _ in range(2)]
    for i in range(2):
        for j in range(2):
            res[i][j] = (a[i][0] * b[0][j] + a[i][1] * b[1][j]) % MOD
    return res

def matrix_power(mat, exponent):
    result = [[1, 0], [0, 1]]  # Identity matrix
    current = [row[:] for row in mat]
    while exponent > 0:
        if exponent % 2 == 1:
            result = matrix_mult(result, current)
        current = matrix_mult(current, current)
        exponent //= 2
    return result

a, b, n = map(int, input().split())

if n == 0:
    print(0)
elif n == 1:
    print(1 % MOD)
else:
    a_mod = a % MOD
    b_mod = b % MOD
    mat = [[a_mod, b_mod], [1, 0]]
    exponent = n - 1
    mat_pow = matrix_power(mat, exponent)
    print(mat_pow[0][0] % MOD)