function main(lines) {
  const [L, R, d] = splitN(lines[0]);

  let res = 0;
  for (let i = L; i <= R; i++) {
    if (i % d === 0) res++;
  }
  
  console.log(res);
}


main( require("fs").readFileSync("/dev/stdin", "utf8").trim().split("\n") );



function splitN(s) {
  return s.split(' ').map(Number);
}