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

if N % X == 0:

  print(((N // X) * T))

else:

  print(((N // X) * T + T))

import sys

 

read = sys.stdin.buffer.read

readline = sys.stdin.buffer.readline

readlines = sys.stdin.buffer.readlines

 

N, X, T = list(map(int, read().split()))

 

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

print((N * T))
N, X, T = list(map(int, input().split()))
if N % X == 0:
    print(((N // X) * T))
else:
    print(((N // X) * T + T))

import sys

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
N, X, T = list(map(int, read().split()))
N = (N + X - 1) // X
print((N * T))

-N, X, T = list(map(int, input().split())) -if N % X == 0: -    print(((N // X) * T)) -else: -    print(((N // X) * T + T)) +import sys + +read = sys.stdin.buffer.read +readline = sys.stdin.buffer.readline +readlines = sys.stdin.buffer.readlines +N, X, T = list(map(int, read().split())) +N = (N + X - 1) // X +print((N * T))