process.stdin.resume();
process.stdin.setEncoding('utf8');
process.stdin.on('data', function (chunk) {
var [N, X] = chunk.split(' ');
if ( (1 <= N && N <= 1000000000) && (1 <= X && X <= 1000) ) console.log((2 * N) / X);
else console.log(`Entrada no válida: N debe estar entre 1 y 10^9 y X debe estar entre 1 y 1000.`);
});
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