题解 | #字符个数统计#

const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;

void async function () {
    // Write your code here
    const line = await readline()
    const arr = []
    for(let i=0; i<line.length;i++){
        if(!arr.includes(line[i])){
            arr.push(line[i])
        }
    }
    console.log(arr.length)

}()