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