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