//Main(`1000 1 1000`);

function Main(input) {
  const [N, X, Y] = input.trim().split(" ").map(Number);

  const divider = parseInt(N / X, 10);

  if (N % X === 0) {
    console.log(divider * Y);
  } else {
    console.log((divider + 1) * Y);
  }
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));