题解 | #汽水瓶#

先借一个来，反正手里总会剩一个的

while(n = Number(readline()) ) {
    console.log(bottleCount(n))
}

function bottleCount(n) {
//     先借一个瓶子，用不用再说
    let bottles = n + 1, drink = 0
    while (bottles >= 3) {
        drink += parseInt(bottles/3);
        bottles = parseInt(bottles / 3) + parseInt(bottles % 3)
    }
    return drink
    
}