# import numpy as np

import sys, math

from itertools import permutations, combinations

from collections import defaultdict, Counter, deque

from math import factorial, gcd

from bisect import bisect_left, bisect_right



sys.setrecursionlimit(10 ** 7)

enu = enumerate

MOD = 10 ** 9 + 7

input = lambda: sys.stdin.readline()[:-1]

pl = lambda x: print(*x, sep="\n")



N, X, T = map(int, input().split())



val = N // X

if N % X == 0:

    print(val * T)

else:

    print((val + 1) * T)

# import numpy as np

import sys, math

from itertools import permutations, combinations

from collections import defaultdict, Counter, deque

from math import factorial, gcd

from bisect import bisect_left, bisect_right



sys.setrecursionlimit(10 ** 7)

enu = enumerate

MOD = 10 ** 9 + 7

input = lambda: sys.stdin.readline()[:-1]

pl = lambda x: print(*x, sep="\n")



N, X, T = map(int, input().split())



val = (N + X - 1) // X

print(val * T)

# import numpy as np
import sys, math
from itertools import permutations, combinations
from collections import defaultdict, Counter, deque
from math import factorial, gcd
from bisect import bisect_left, bisect_right

sys.setrecursionlimit(10**7)
enu = enumerate
MOD = 10**9 + 7
input = lambda: sys.stdin.readline()[:-1]
pl = lambda x: print(*x, sep="\n")
N, X, T = map(int, input().split())
val = N // X
if N % X == 0:
    print(val * T)
else:
    print((val + 1) * T)

# import numpy as np
import sys, math
from itertools import permutations, combinations
from collections import defaultdict, Counter, deque
from math import factorial, gcd
from bisect import bisect_left, bisect_right

sys.setrecursionlimit(10**7)
enu = enumerate
MOD = 10**9 + 7
input = lambda: sys.stdin.readline()[:-1]
pl = lambda x: print(*x, sep="\n")
N, X, T = map(int, input().split())
val = (N + X - 1) // X
print(val * T)

-val = N // X -if N % X == 0: -    print(val * T) -else: -    print((val + 1) * T) +val = (N + X - 1) // X +print(val * T)