Binge Watch

'use strict';

const fs = require('fs');

process.stdin.resume();
process.stdin.setEncoding('utf-8');

let inputString = '';
let currentLine = 0;

process.stdin.on('data', function(inputStdin) {
    inputString += inputStdin;
});

process.stdin.on('end', function() {
    inputString = inputString.split('\n');

    main();
});

function readLine() {
    return inputString[currentLine++];
}



/*
 * Complete the 'findMinimumDays' function below.
 *
 * The function is expected to return an INTEGER.
 * The function accepts FLOAT_ARRAY durations as parameter.
 */

function findMinimumDays(durations) {
    // Write your code here
    durations=durations.sort((a,b)=>a-b);
    let left=0; 
    let right=durations.length-1;
    let days=0;
    
    while(left<=right){
        if(left==right){
            days++;
            break;
        }
        
        if(durations[left]+durations[right]<=3.0){
            left++;
            right--;
            days++;
        }
        
        else{
            right--;
            days++
        }
    }
return days;
}

function main() {
    const ws = fs.createWriteStream(process.env.OUTPUT_PATH);

    const durationsCount = parseInt(readLine().trim(), 10);

    let durations = [];

    for (let i = 0; i < durationsCount; i++) {
        const durationsItem = parseFloat(readLine().trim());
        durations.push(durationsItem);
    }

    const result = findMinimumDays(durations);

    ws.write(result + '\n');

    ws.end();
}