a, b, c = map(int, raw_input().split())

high = 1e18
low = 0

while high - low > 1:
    mid = int((high + low) / 2)
    year = int(mid / a)
    money = int(mid + year * b - year)

    if money >= c:
        high = mid
    else:
        low = mid

print(high)