l,r,n=map(int,input().split()) cnt=[0]*n v1=l//n+1 if l%n!=0 else l//n v2=r//n for i in range(n): ans=v2-v1 if i>=l%n and l%n!=0: ans+=1 if i<=r%n and r%n!=0: ans+=1 if n==1: ans+=1 print(ans)