#pragma region kyomukyomupurin

/**
 *    author  : 𝒌𝒚𝒐𝒎𝒖𝒌𝒚𝒐𝒎𝒖𝒑𝒖𝒓𝒊𝒏
 *    created : 2020-07-05 22:45:07
 **/

#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <chrono>
#include <cmath>
#include <complex>
#include <cstring>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <utility>
#include <vector>

using namespace std;

using int64 = long long;

template<class T>
inline void eraque(std::vector<T>& vec) {
  vec.erase(std::unique(vec.begin(), vec.end()), vec.end());
  return;
}

template<class T>
inline int lower_position(const std::vector<T>& vec, T value) {
  return static_cast<int>(std::distance(vec.begin(), std::lower_bound(vec.begin(), vec.end(), value)));
}

template<class T>
inline int upper_position(const std::vector<T>& vec, T value) {
  return static_cast<int>(std::distance(vec.begin(), std::upper_bound(vec.begin(), vec.end(), value)));
}

template<class T>
std::string to_binary(T n) {
  assert(n > 0);
  std::string ret = "";
  while (n) ret += (n & 1) ? '1' : '0', n >>= 1;
  std::reverse(ret.begin(), ret.end());
  return ret;
}

template <class T>
using binary_heap = std::priority_queue<T, std::vector<T>, std::greater<T>>;

template <class T, class U>
std::ostream& operator<<(std::ostream& os, const std::pair<T, U>& p) {
  return os << '(' << p.first << ", " << p.second << ')';
}

template <class Tuple, std::size_t... Is>
void tuple_out(std::ostream& os, const Tuple& tp, std::index_sequence<Is...>) {
  ((os << (Is ? ", " : "(") << std::get<Is>(tp)), ...) << ")";
}

template <class... Args>
std::ostream& operator<<(std::ostream& os, const std::tuple<Args...>& tp) {
  tuple_out(os, tp, std::index_sequence_for<Args...>{});
  return os;
}

template <class T>
std::ostream& operator<<(std::ostream& os, const std::vector<T>& vec) {
  int n = 0;
  for (auto e : vec) os << (n++ ? ", " : "{") << e;
  return os << (n ? "}" : "{}");
}

template <class T, class Compare>
std::ostream& operator<<(std::ostream& os, const std::set<T, Compare>& st) {
  int n = 0;
  for (auto e : st) os << (n++ ? ", " : "{") << e;
  return os << (n ? "}" : "{}");
}

template <class T, class U, class Compare>
std::ostream& operator<<(std::ostream& os, const std::map<T, U, Compare>& mp) {
  int n = 0;
  for (auto e : mp) os << (n++ ? ", " : "{") << e;
  return os << (n ? "}" : "{}");
}

template <class T>
std::istream& operator>>(std::istream& is, std::vector<T>& vec) {
  for (T& e : vec) is >> e;
  return is;
}

template <class T, class U>
std::istream& operator>>(std::istream& is, std::pair<T, U>& p) {
  return is >> p.first >> p.second;
}

template <class Tuple, std::size_t... Is>
void tuple_in(std::istream& is, Tuple& tp, std::index_sequence<Is...>) {
  ((is >> std::get<Is>(tp)), ...);
}

template <class... Args>
std::istream& operator>>(std::istream& is, std::tuple<Args...>& tp) {
  tuple_in(is, tp, std::index_sequence_for<Args...>{});
  return is;
}

#define all(_) begin(_), end(_)
#define rall(_) rbegin(_), rend(_)

#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]: ", debug_out(__VA_ARGS__)
#else
#define debug(...)
#endif

void debug_out() { std::cerr << '\n'; }

template <class Head, class... Tail>
void debug_out(Head&& head, Tail&&... tail) {
  std::cerr << head;
  if (sizeof...(Tail) != 0) std::cerr << ", ";
  debug_out(std::forward<Tail>(tail)...);
}

#pragma endregion kyomukyomupurin

namespace FastIO {
class Scanner {
  static constexpr int buf_size = (1 << 18);
  static constexpr int integer_size = 20;
  char buf[buf_size] = {};
  char *cur = buf, *ed = buf;

 public:
  Scanner() {}

  template <class T>
  inline Scanner& operator>>(T& val) {
    read(val);
    return *this;
  }

 private:
  inline void reload() {
    size_t len = ed - cur;
    memmove(buf, cur, len);
    char* tmp = buf + len;
    ed = tmp + fread(tmp, 1, buf_size - len, stdin);
    *ed = 0;
    cur = buf;
  }

  inline void skip_space() {
    while (true) {
      if (cur == ed) reload();
      while (*cur == ' ' || *cur == '\n') ++cur;
      if (__builtin_expect(cur != ed, 1)) return;
    }
  }

  template <class T, std::enable_if_t<std::is_same<T, int>::value, int> = 0>
  inline void read(T& num) {
    skip_space();
    if (cur + integer_size >= ed) reload();
    bool neg = false;
    num = 0;
    if (*cur == '-') neg = true, ++cur;
    while (*cur >= '0') num = num * 10 + (*cur ^ 48), ++cur;
    if (neg) num = -num;
  }

  template <class T, std::enable_if_t<std::is_same<T, int64>::value, int> = 0>
  inline void read(T& num) {
    skip_space();
    if (cur + integer_size >= ed) reload();
    bool neg = false;
    num = 0;
    if (*cur == '-') neg = true, ++cur;
    while (*cur >= '0') num = num * 10 + (*cur ^ 48), ++cur;
    if (neg) num = -num;
  }

  template <class T,
            std::enable_if_t<std::is_same<T, std::string>::value, int> = 0>
  inline void read(T& str) {
    skip_space();
    if (cur + str.size() >= ed) reload();
    auto it = cur;
    while (!(*cur == ' ' || *cur == '\n')) ++cur;
    str = std::string(it, cur);
  }

  template <class T, std::enable_if_t<std::is_same<T, char>::value, int> = 0>
  inline void read(T& c) {
    skip_space();
    if (cur + 1 >= ed) reload();
    c = *cur, ++cur;
  }

  template <class T, std::enable_if_t<std::is_same<T, double>::value, int> = 0>
  inline void read(T& num) {
    skip_space();
    if (cur + integer_size >= ed) reload();
    bool neg = false;
    num = 0;
    if (*cur == '-') neg = true, ++cur;
    while (*cur >= '0' && *cur <= '9') num = num * 10 + (*cur - '0'), ++cur;
    if (*cur != '.') return;
    ++cur;
    T base = 0.1;
    while (*cur >= '0' && *cur <= '9') {
      num += base * (*cur - '0');
      ++cur;
      base *= 0.1;
    }
    if (neg) num = -num;
  }

  template <class T,
            std::enable_if_t<std::is_same<T, long double>::value, int> = 0>
  inline void read(T& num) {
    skip_space();
    if (cur + integer_size >= ed) reload();
    bool neg = false;
    num = 0;
    if (*cur == '-') neg = true, ++cur;
    while (*cur >= '0' && *cur <= '9') num = num * 10 + (*cur - '0'), ++cur;
    if (*cur != '.') return;
    ++cur;
    T base = 0.1;
    while (*cur >= '0' && *cur <= '9') {
      num += base * (*cur - '0');
      ++cur;
      base *= 0.1;
    }
    if (neg) num = -num;
  }

  template <class T>
  inline void read(std::vector<T>& vec) {
    for (T& e : vec) read(e);
  }

  template <class T, class U>
  inline void read(std::pair<T, U>& p) {
    read(p.first, p.second);
  }

  template <class Tuple, std::size_t... Is>
  inline void tuple_scan(Tuple& tp, std::index_sequence<Is...>) {
    (read(std::get<Is>(tp)), ...);
  }

  template <class... Args>
  inline void read(std::tuple<Args...>& tp) {
    tuple_scan(tp, std::index_sequence_for<Args...>{});
  }

  inline void read() {}

  template <class Head, class... Tail>
  inline void read(Head&& head, Tail&&... tail) {
    read(head);
    read(std::forward<Tail>(tail)...);
  }
};

class Printer {
  static constexpr int buf_size = (1 << 18);
  static constexpr int integer_size = 20;
  static constexpr int margin = 1;
  static constexpr int n = 10000;
  char buf[buf_size + margin] = {};
  char integer[integer_size + margin] = {};
  char table[n * 4] = {};
  char* cur = buf;

 public:
  constexpr Printer() { build(); }

  ~Printer() { flush(); }

  template <class T>
  inline Printer& operator<<(T val) {
    write(val);
    return *this;
  }

 private:
  constexpr void build() {
    for (int i = 0; i < 10000; ++i) {
      int tmp = i;
      for (int j = 3; j >= 0; --j) {
        table[i * 4 + j] = tmp % 10 + '0';
        tmp /= 10;
      }
    }
  }

  inline void flush() {
    fwrite(buf, 1, cur - buf, stdout);
    cur = buf;
  }

  template <class T, std::enable_if_t<std::is_same<T, int>::value, int> = 0>
  inline int get_digit(T n) {
    if (n >= (int)1e5) {
      if (n >= (int)1e8) return 9;
      if (n >= (int)1e7) return 8;
      if (n >= (int)1e6) return 7;
      if (n >= (int)1e5) return 6;
    } else {
      if (n >= (int)1e4) return 5;
      if (n >= (int)1e3) return 4;
      if (n >= (int)1e2) return 3;
      if (n >= (int)1e1) return 2;
      return 1;
    }
  }

  template <class T, std::enable_if_t<std::is_same<T, int64>::value, int> = 0>
  inline int get_digit(T n) {
    if (n >= (int64)1e10) {
      if (n >= (int64)1e14) {
        if (n >= (int64)1e18) return 19;
        if (n >= (int64)1e17) return 18;
        if (n >= (int64)1e16) return 17;
        if (n >= (int64)1e15) return 16;
        return 15;
      } else {
        if (n >= (int64)1e14) return 15;
        if (n >= (int64)1e13) return 14;
        if (n >= (int64)1e12) return 13;
        if (n >= (int64)1e11) return 12;
        return 11;
      }
    } else {
      if (n >= (int64)1e5) {
        if (n >= (int64)1e9) return 10;
        if (n >= (int64)1e8) return 9;
        if (n >= (int64)1e7) return 8;
        if (n >= (int64)1e6) return 7;
        return 6;
      } else {
        if (n >= (int64)1e4) return 5;
        if (n >= (int64)1e3) return 4;
        if (n >= (int64)1e2) return 3;
        if (n >= (int64)1e1) return 2;
        return 1;
      }
    }
  }

  template <class T, std::enable_if_t<std::is_same<T, int>::value, int> = 0>
  inline void write(T num) {
    if (__builtin_expect(cur + integer_size >= buf + buf_size, 0)) flush();
    if (num == 0) {
      write('0');
      return;
    }
    if (num < 0) {
      write('-');
      num = -num;
    }
    int len = get_digit(num);
    int digits = len;
    while (num >= 10000) {
      memcpy(cur + len - 4, table + (num % 10000) * 4, 4);
      num /= 10000;
      len -= 4;
    }
    memcpy(cur, table + num * 4 + (4 - len), len);
    cur += digits;
  }

  template <class T, std::enable_if_t<std::is_same<T, int64>::value, int> = 0>
  inline void write(T num) {
    if (__builtin_expect(cur + integer_size >= buf + buf_size, 0)) flush();
    if (num == 0) {
      write('0');
      return;
    }
    if (num < 0) {
      write('-');
      num = -num;
    }
    int len = get_digit(num);
    int digits = len;
    while (num >= 10000) {
      memcpy(cur + len - 4, table + (num % 10000) * 4, 4);
      num /= 10000;
      len -= 4;
    }
    memcpy(cur, table + num * 4 + (4 - len), len);
    cur += digits;
  }

  template <class T, std::enable_if_t<std::is_same<T, char>::value, int> = 0>
  inline void write(T c) {
    if (__builtin_expect(cur + 1 >= buf + buf_size, 0)) flush();
    *cur = c;
    ++cur;
  }

  template <class T,
            std::enable_if_t<std::is_same<T, std::string>::value, int> = 0>
  inline void write(T str) {
    if (__builtin_expect(cur + str.size() >= buf + buf_size, 0)) flush();
    for (char c : str) write(c);
  }
};
}  // namespace FastIO

FastIO::Scanner fin;
FastIO::Printer fout;


int main() {
  //ios_base::sync_with_stdio(false);
  //cin.tie(nullptr);

  int n; cin >> n;
  int need = (n + 1000 - 1) / 1000;
  fout << need * 1000 - n << '\n';

  return 0;
}


Measured memory_bytes: 4008