I don't know why I'm getting wrong answer 100%.

const inputFileRaw = require('fs').readFileSync('/dev/stdin', 'utf8');
const inputLines = inputFileRaw.split('\n');

(() => {
    for (let currLine = 0; currLine < inputLines.length;) {
        if (!inputLines[currLine]) break;

        // Getting number of boxes
        const boxesNumber = Number(inputLines[currLine]);
        currLine++;

        // Filling the boxes
        const boxes = {};
        for (let boxIx = 0; boxIx < boxesNumber; boxIx++, currLine++) {
            const [leftIx, rightIx] = inputLines[currLine].split(' ').map(value => Number(value));
            for (let fillIx = leftIx; fillIx <= rightIx; fillIx++) {
                boxes[fillIx] = boxes[fillIx] ? boxes[fillIx] + 1 : 1;
            }
        }

        // Getting searching number
        const mangoSearch = Number(inputLines[currLine]);
        currLine++;

        // Searching for screws
        let found = false;
        for (let currSize = 1, currStep = 0; currSize <= 100; currSize++) {
            if (mangoSearch == currSize && boxes[currSize]) {
                console.log(`${mangoSearch} found from ${currStep} to ${currStep + boxes[currSize] - 1}`);
                found = true;
                break;
            }
            if (boxes[currSize]) {
                currStep += boxes[currSize];
            }
        }
        if (!found) {
            console.log(`${mangoSearch} not found`);
        }
    }
})();