def _mul(A, B, MOD):
    C = [[0] * len(B[0]) for i in range(len(A))]
    for i in range(len(A)):
        for k in range(len(B)):
            for j in range(len(B[0])):
                C[i][j] = (C[i][j] + A[i][k]*B[k][j]) % MOD
    return C

#A**n
def pow_matrix(A, n, MOD):
    B = [[0] * len(A) for i in range(len(A))]
    for i in range(len(A)):
        B[i][i] = 1
    while n > 0:
        if n & 1:
            B = _mul(A, B, MOD)
        A = _mul(A, A, MOD)
        n  = n // 2
    return B

a, b, n = map(int, input().split())
MOD = 10**9 + 7
x0 = 0
x1 = 1
x2 = a*x1 + b*x0
matrix = [[a, b, 0], [1, 0, 0], [0, 1, 0]]

ans_matrix = pow_matrix(matrix, n, MOD)
ans = ans_matrix[2][0]*x2 + ans_matrix[2][1]*x1 + ans_matrix[2][2]*x0 
print(ans % MOD)