题解 | #挑7#

package main

import (
	"fmt"
	"strconv"
	"strings"
)

func main() {
	var n int
	fmt.Scan(&n)

	var ret []int
	for i := 1; i <= n; i++ {
		if i%7 == 0 {
			ret = append(ret, i)

			continue
		}

		if strings.Contains(strconv.Itoa(i), "7") {
			ret = append(ret, i)
		}
	}

	fmt.Println(len(ret))
}