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