X = abs(int(input()))
Y = int(input())
L = int(input())
C = (X//L+1 if X%L!=0 else X//L) + (Y//L+1 if Y%L!=0 else Y//L)
if Y>=0 and X>0:
    C += 1
elif Y<0:
    C += 2
elif Y == 0 and X != 0:
    C += 2  
print(C)