๐งธ ์ฒ์ ์๋ํ ์ฝ๋๋ ๋ฉ๋ชจ๋ฆฌ ์ด๊ณผ๊ฐ ๋ฐ์ํด ๋ค๋ฅธ ๋ฐฉ๋ฒ์ ์๊ฐํ๋ค. maxEnd๋ฅผ 0์ผ๋ก ํ๊ณ ์ค๋ ํค๋งธ๋๋ฐ ๋ฐ๋ก๋ฅผ ์ฐพ์ ํด๊ฒฐํ ์ ์์๋ค.
์ ๋ต ์ฝ๋
const fs = require('fs');
const input = fs.readFileSync('/dev/stdin').toString().trim().split("\n").map((item) => item.split(" ").map(Number));
const N = input.shift();
input.sort((a, b) => a[0] - b[0]);
let count=0;
let maxEnd = -1000000001;
for (let i = 0; i < N; i++) {
const [start, end] = input[i];
if (maxEnd <= start) {
count += end - start;
} else if (end > maxEnd) {
count += end - maxEnd;
}
if (maxEnd < end) {
maxEnd = end;
}
}
console.log(count.toString());