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