题解 | #字符个数统计#

map记录即可

package main

import (
	"bufio"
	"fmt"
	"os"
)

func main() {
	var s string
	in := bufio.NewReader(os.Stdin)
	fmt.Fscan(in, &s)
	mp := make(map[byte]bool)
	for _, v := range s {
		mp[byte(v)] = true
	}
	fmt.Println(len(mp))
}