X=[int(input()) for i in range(3)]
L=X[2]
if X[0]<0:
    X[0]=-1*X[0]
N=1
if X[0]==0:
    N=0
if X[1]<0:
    X[1]=-1*X[1]
    N+=1
    if X[0]==0:
        N+=1
i=0
for i in range(2):
    s=X[i]//L
    if s*L==X[i]:
        N+=s
    else:
        N+=s+1
print(N)