A, B = map(int, input().split())
N = int(input())
mod = int(1e9) + 7
def matprod(m1, m2, n, l, m):
    y = [[0 for _ in range(m)] for __ in range(n)]
    for i in range(n):
        for j in range(m):
            for k in range(l):
                y[i][j] += m1[i][k] * m2[k][j] % mod
                y[i][j] %= mod
    return y
    
def matpow(m1, n, m):
    y = [[i==j for j in range(n)] for i in range(n)]
    bas = [[m1[i][j] for j in range(n)] for i in range(n)]
    tmp = m
    while tmp != 0:
        if tmp % 2 == 1:
            y = matprod(y, bas, n, n, n)[:][:]
        bas = matprod(bas, bas, n, n, n)[:][:]
        tmp //= 2
    return y
mat = matpow([[A, B], [1, A]], 2, N)
print(2*mat[0][0]%mod)