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
   let str = await readline();
   let charArr = str.split('');
   let qcStr = '';
   charArr.forEach(char=>{
    if(qcStr.indexOf(char)== -1){
        qcStr+=char;
    }
   });
   console.log(qcStr.length);
}()