process.stdin.resume();
process.stdin.setEncoding('utf8');
var remainder = '';
var inputLines = [];
process.stdin.on('data', function (chunk) {
var lines = chunk.toString().split('\n');
lines.unshift(remainder + lines.shift());
remainder = lines.pop();
inputLines = inputLines.concat(lines);
});
process.stdin.on('end', function () {
if (remainder) {
inputLines.push(remainder);
}
const N = parseInt(inputLines[0].trim(), 10);
const X = parseInt(inputLines[1].trim(), 10);
const totalCaras = 2 * N;
const tiempoMinimo = Math.ceil(totalCaras / X);
process.stdout.write(tiempoMinimo + '\n');
});
// Complejidad del algoritmo: O(1)
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