'use strict';

function Main(input) {
    // N X T
    const [N, X, T] = input
        .trim()
        .split(' ')
        .map((v) => Number(v));
    console.log(N, X, T);

    const result = Math.ceil(N / X) * T;

    console.log(result);
    return;
}
Main(require('fs').readFileSync('/dev/stdin', 'utf8'));