function Main(input) {
  let lines = input.split("\n");
  lines.pop();
  lines = lines[0].split(" ");
  fnum = parseInt(lines[0]);
  lnum = parseInt(lines[1]);
  multiple = parseInt(lines[2]);
  let count = 0;
  for(let i = fnum; i <= lnum; i++){
  	if(i%multiple === 0) count++;
  }
  console.log(count);
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));