import sys



readline = sys.stdin.readline

MOD = 10 ** 9 + 7

INF = float('INF')

sys.setrecursionlimit(10 ** 5)





def main():

    n, x, t = list(map(int, readline().split()))

    print(((n + x - 1) // x * t))





if __name__ == '__main__':

    main()

from math import ceil

n, x, t = list(map(int, input().split()))

k = ceil(n / x)

print((k * t))
import sys

readline = sys.stdin.readline
MOD = 10**9 + 7
INF = float("INF")
sys.setrecursionlimit(10**5)


def main():
    n, x, t = list(map(int, readline().split()))
    print(((n + x - 1) // x * t))


if __name__ == "__main__":
    main()

from math import ceil

n, x, t = list(map(int, input().split()))
k = ceil(n / x)
print((k * t))

-import sys +from math import ceil -readline = sys.stdin.readline -MOD = 10**9 + 7 -INF = float("INF") -sys.setrecursionlimit(10**5) - - -def main(): -    n, x, t = list(map(int, readline().split())) -    print(((n + x - 1) // x * t)) - - -if __name__ == "__main__": -    main() +n, x, t = list(map(int, input().split())) +k = ceil(n / x) +print((k * t))