V, T, P = map(int, input().split())

def compute_k_last(V, T):
    if T == 1:
        return 0
    k = V // (T - 1) + 1
    if (k - 1) * (T - 1) > V:
        k -= 1
    return k

if P == 0:
    k_last = compute_k_last(V, T)
    print(V + k_last)
else:
    def compute_k_max_p(V, T):
        low, high = 1, V + 1
        best = 0
        while low <= high:
            mid = (low + high) // 2
            required = (mid - 1) * T + 1
            if V + mid >= required:
                best = mid
                low = mid + 1
            else:
                high = mid - 1
        return best

    k_max_p = compute_k_max_p(V, T)
    block_time = V + k_max_p
    total_p = block_time * P

    k_last = compute_k_last(V, T)
    total_last = V + k_last

    print(total_p + total_last)