题解 | #字符个数统计#

const readline = require('readline');

const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});
let num = 0;
rl.on('line', function (line) {
    let tokens:Array<string> = line.split('');
    let str:string;
    while(tokens.length){
        str = tokens.splice(0,1)[0];
        if(!tokens.includes(str)){
            num++
        }
    }
    console.log(num)
});