#include <bits/stdc++.h>
int main(int argc, char const* argv[]) {
  int a, b, c;
  int sum = 0;
  std::cin >> a >> b >> c;
  for (int i = a; i <= b; i++) {
    if (!(i % c)) {
      sum++;
    }
  }
  std::cout << sum << std::endl;
  return 0;
}
