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