#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c, count, mod;
  count = 0;
  cin >> a >> b >> c;
  for (int i = a; i <= b; i++) {
    mod = i % c;
    if (mod == 0) {
      count += 1;
    }
  }
  cout << count << endl;
  return 0;
}
