题解 | #字符个数统计#

const readline = require('readline');
const rl = readline.createInterface({
    input:process.stdin,
    output:process.stdout
});
rl.on('line',(line)=>{
//     let res = [];
//     for(let i of line){
//         if(!res.includes(i)){
//             res.push(i)
//         }
//     }
//     console.log(res.length)
    let arr = line.split('');
    console.log(Array.from(new Set(arr)).length)
})