// 数组去重, 数组排序
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
while(line = await readline()){
const count = [];
const a = line.split('');
const b = a.sort();
for (let i = 0; i < b.length; i++) {
if (count.indexOf(b[i]) === -1) {
count.push(b[i]);
}
}
console.log(count.length);
}
}()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
while(line = await readline()){
const count = [];
const a = line.split('');
const b = a.sort();
for (let i = 0; i < b.length; i++) {
if (count.indexOf(b[i]) === -1) {
count.push(b[i]);
}
}
console.log(count.length);
}
}()