paiza

s4p3.js

"use strict";
process.stdin.resume();
process.stdin.setEncoding('utf8');
// 自分の得意な言語で
// Let's チャレンジ！！
process.stdin.on('data', function (chunk) {
    let items = chunk.split('\n');
    let conditions = items[0].split(' ');
    let rangeLength = parseInt(conditions[0]);
    let attackLength = parseInt(conditions[1]);
    let loopLength = attackLength - rangeLength + 1;
    
    let lastAttack = 0;
    for (let i = 1; i <= rangeLength; i++) {
        lastAttack += (+items[i]);
    }
    let maxAttack = lastAttack;
    for (let i = 1; i < loopLength; i++) {
        lastAttack = lastAttack - parseInt(items[i]) + parseInt(items[i + rangeLength]);
        if (lastAttack > maxAttack) {
            maxAttack = lastAttack;
        }
    }
    
    console.log(maxAttack);
});