import sys, os, math, bisect, itertools, collections, heapq, queue

# from scipy.sparse.csgraph import csgraph_from_dense, floyd_warshall

from decimal import Decimal

from collections import defaultdict, deque



sys.setrecursionlimit(10000000)



ii = lambda: int(sys.stdin.buffer.readline().rstrip())

il = lambda: list(map(int, sys.stdin.buffer.readline().split()))

fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))

iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]



iss = lambda: sys.stdin.buffer.readline().decode().rstrip()

sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))

isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]



lcm = lambda x, y: (x * y) // math.gcd(x, y)



MOD = 10 ** 9 + 7

MAX = float('inf')





def main():

    if os.getenv("LOCAL"):

        sys.stdin = open("input.txt", "r")



    N = ii()

    n = 1

    while True:

        if n * 1000 >= N:

            print(((n * 1000) - N))

            exit()

        else:

            n += 1





if __name__ == '__main__':

    main()

import sys, os, math, bisect, itertools, collections, heapq, queue

# from scipy.sparse.csgraph import csgraph_from_dense, floyd_warshall

from decimal import Decimal

from collections import defaultdict, deque



sys.setrecursionlimit(10000000)



ii = lambda: int(sys.stdin.buffer.readline().rstrip())

il = lambda: list(map(int, sys.stdin.buffer.readline().split()))

fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))

iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]



iss = lambda: sys.stdin.buffer.readline().decode().rstrip()

sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))

isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]



lcm = lambda x, y: (x * y) // math.gcd(x, y)



MOD = 10 ** 9 + 7

MAX = float('inf')





def main():

    if os.getenv("LOCAL"):

        sys.stdin = open("input.txt", "r")



    N = ii()

    print(((1000 - N % 1000) % 1000))





if __name__ == '__main__':

    main()

import sys, os, math, bisect, itertools, collections, heapq, queue

# from scipy.sparse.csgraph import csgraph_from_dense, floyd_warshall
from decimal import Decimal
from collections import defaultdict, deque

sys.setrecursionlimit(10000000)
ii = lambda: int(sys.stdin.buffer.readline().rstrip())
il = lambda: list(map(int, sys.stdin.buffer.readline().split()))
fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))
iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]
iss = lambda: sys.stdin.buffer.readline().decode().rstrip()
sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))
isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]
lcm = lambda x, y: (x * y) // math.gcd(x, y)
MOD = 10**9 + 7
MAX = float("inf")


def main():
    if os.getenv("LOCAL"):
        sys.stdin = open("input.txt", "r")
    N = ii()
    n = 1
    while True:
        if n * 1000 >= N:
            print(((n * 1000) - N))
            exit()
        else:
            n += 1


if __name__ == "__main__":
    main()

import sys, os, math, bisect, itertools, collections, heapq, queue

# from scipy.sparse.csgraph import csgraph_from_dense, floyd_warshall
from decimal import Decimal
from collections import defaultdict, deque

sys.setrecursionlimit(10000000)
ii = lambda: int(sys.stdin.buffer.readline().rstrip())
il = lambda: list(map(int, sys.stdin.buffer.readline().split()))
fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))
iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]
iss = lambda: sys.stdin.buffer.readline().decode().rstrip()
sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))
isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]
lcm = lambda x, y: (x * y) // math.gcd(x, y)
MOD = 10**9 + 7
MAX = float("inf")


def main():
    if os.getenv("LOCAL"):
        sys.stdin = open("input.txt", "r")
    N = ii()
    print(((1000 - N % 1000) % 1000))


if __name__ == "__main__":
    main()

-    n = 1 -    while True: -        if n * 1000 >= N: -            print(((n * 1000) - N)) -            exit() -        else: -            n += 1 +    print(((1000 - N % 1000) % 1000))