๐งธ ์คํ ๊ธฐ๋ณธ ๋ฌธ์ ์ด๋ค.
์ฝ๋
const fs = require('fs');
const input = fs.readFileSync('/dev/stdin').toString().trim().split('\n').map(Number);
const K = input.shift();
const stack = [];
for (let num of input) {
if (num == 0) stack.pop();
else stack.push(num);
}
console.log(stack.reduce((a, b) => a + b, 0));