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export default function preimageSizeFZF(k: number): number {    let left = 0, right = k;    while (left <= right) {        const mid = Math.floor((right + left) / 2);
        const basic = calc(mid);        if (basic == k) return 5;
        if (basic < k) left = mid + 1;        if (basic > k) right = mid - 1;    }    return 0;}
function calc(b: number) {    return Array<number>(1 + Math.ceil(Math.log(10 ** 9) / Math.log(5))).fill(0)        .reduce((a, _, i) => Math.floor(a + b / Math.pow(5, i)), 0);}