56. 绘图机器

const readline = require('readline');
const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
});
let lines = [];
let n = 0;
let e = 0;
rl.on('line', function(line) {
    lines.push(line);
    if (lines.length === 1) {
        [n, e] = line.split(' ').map(Number);
        if (e === 0) {
            console.log(0);
            return;
        }
    }
    if (e !== 0 && n !== 0 && lines.length === n+1) {
        lines.shift();
        const offsets = new Array(e).fill(0);
        for(const line of lines) {
            const [x, offsetY] = line.split(' ').map(Number);
            offsets[x] = offsetY;
        }
        const dp = new Array(e).fill(0);
        dp[0] = offsets[0];
        for(let i=1; i<e; i++) {
            dp[i] = dp[i-1] + offset[i];
        }
        let ans = 0;
        for(const num of dp) {
            ans += Math.abs(num);
        }
        console.log(ans);
    }
});