a, b, N = map(int, input().split())
M = 10**9 + 7

RA = RD = 1; RB = RC = 0
XA = a; XB = b; XC = 1; XD = 0
while N:
    if N & 1:
        RA, RB, RC, RD = (RA*XA + RB*XC) % M, (RA*XB + RB*XD) % M, (RC*XA + RD*XC) % M, (RC*XB + RD*XD) % M
    XA, XB, XC, XD = (XA**2 + XB*XC) % M, XB*(XA + XD) % M, XC*(XA + XD) % M, (XB*XC + XD**2) % M
    N >>= 1

print(RC)