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