"use strict";

const main = arg => {
  const input = arg.trim().split(' ').map(x => parseInt(x));

  const [L, R, d] = input;

  const ans = [];

  for (let i = L; i <= R; i++) {
    if (!(i % d)) {
      ans.push(i);
    }
  }

  console.log(ans.length);

}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));  