#include <bits/stdc++.h>
using namespace std;
using ll = long long int;
using vi = vector<int>;
using vvi = vector<vector<int>>;
using vll = vector<ll>;
using vb = vector<bool>;
using vvb = vector<vector<bool>>;
using vs = vector<string>;
using pii = pair<int, int>;
using pis = pair<int, string>;
using msi = map<string, int>;
template <typename T>
void say(T s) {
  cout << s << "\n";
}
template <typename T>
void say(vector<T> s) {
  auto itr = s.begin();
  cout << *(itr++);
  while (itr != s.end()) {
    cout << " " << *(itr++);
  }
  cout << "\n";
}
template <typename T>
void say(vector<T> s, string t) {
  auto itr = s.begin();
  cout << *(itr++);
  while (itr != s.end()) {
    cout << t << *(itr++);
  }
  cout << "\n";
}
void yn(bool b) {
  if (b)
    say("yes");
  else
    say("no");
}
void Yn(bool b) {
  if (b)
    say("Yes");
  else
    say("No");
}
void YN(bool b) {
  if (b)
    say("YES");
  else
    say("NO");
}
template <typename T>
void maxi(T& a, T b) {
  a = max(a, b);
}
template <typename T>
void mini(T& a, T b) {
  a = min(a, b);
}
void exact_say(double x) {
  cout << setprecision(numeric_limits<double>::max_digits10) << x << endl;
}
template <class T>
void getVector(vector<T>& v) {
  for (int i = 0; i < v.size(); ++i) cin >> v[i];
}
bool in(int w, int x, int r) { return x - r >= 0 && x + r <= w; }
int main() {
  int ans = 0;
  int a;
  cin >> a;
  ;
  int b;
  cin >> b;
  ;
  int c;
  cin >> c;
  ;
  for (int i = a; i <= b; ++i) {
    if (i % c == 0) ++ans;
  }
  say(ans);
}
