def solve():
    A, B, T = list(map(int, input().split()))

    mi = T + A + B
    for y in range(A):
        if B * y > T:
            break
        x = (T - y * B + A - 1) // A
        mi = min(mi, A * x + B * y)

    print(mi)


def main():
    solve()


if __name__ == '__main__':
    main()