题解 | #自守数#

let line;

function func(line) {
    const num = parseInt(line);
    let count = 0;
    for(let i = 0; i <= num; i++) {
        const sum = i * i;
        const len = String(i).length;
        // 获取尾部数字
        const endNum = parseInt(String(sum).substr(String(sum).length - len,len));
        if (endNum === i) count++;
    }
    return count;
}

while(line = readline()) {
    print(func(line));
}