#include <bits/stdc++.h>
int main() {
  int a, b, c;
  int d = 0;
  scanf("%d %d %d\n", &a, &b, &c);
  for (int x = a; x <= b; x++) {
    if (x % c == 0)
      d++;
    else
      ;
  }
  printf("%d\n", d);
  return 0;
}
