题解 | #字符个数统计#

package main

import "fmt"

func main() {
	var str string
	fmt.Scan(&str)
	m := make(map[byte]bool)
	for i := range str {
		if _, ok := m[str[i]]; !ok {
			m[str[i]] = true
		}
	}
	fmt.Println(len(m))
}