function nth1(n) {
let s = "";
let c = 1;
while (1) {
s += c++;
if (s.length >= n) return s[n - 1];
}
}
function nth2(n) {
const nine = 9;
let sum = 0;
let dist = 0;
let len = 0;
while (1) {
sum += nine * len;
dist += nine;
if (sum >= n) {
sum -= nine * len;
dist -= nine;
n -= sum;
break;
}
nine *= 10;
len++;
}
const diff = Math.ceil(n / len);
const d = n % len || len;
return (dist + diff + "").charAt(d - 1);
}