from decimal import ROUND_HALF_UP, Decimal


def main():
    b = list(map(Decimal, input().split()))
    if b[0] == b[1]:
        print(b[0])
        return
    r = ((b[2]-b[1])/(b[1]-b[0]))
    d = b[1] - r*b[0]
    print((r*b[2]+d).quantize(Decimal("0"), rounding=ROUND_HALF_UP))


if __name__ == "__main__":
    main()