l,r,c=map(int,input().split())

if r-l < 100000:
    ans = 10**10
    for i in range(l,r+1):
        t=i*c
        ans=min(1000-t%1000,ans)
        if t >= 1000:
            ans=min(t%1000,ans)
    print(ans)
    exit()
        

t=l*c // 1000
t1=r*c// 1000

if t1 - t > 0:
    print(0)
else:
    ans = 10**10
    for i in range(l,r+1):
        t=i*c
        ans=min(1000-t%1000,ans)
        if t >= 1000:
            ans=min(t%1000,ans)
    print(ans)