蓝桥杯 1的个数

import java.util.Scanner;

public class Main {

	static Scanner sc = new Scanner(System.in);
	
	public static void main(String[] args) {
		int n = sc.nextInt();
		int num = 0;
		for (int i = 1; i <= n; i++) {
			String str = String.valueOf(i);
			for (int j = 0; j < str.length(); j++) {
				if(String.valueOf(str.charAt(j)).equals("1")) {
					num = num + 1;
				}
			}
		}
		System.out.println(num);
	}
	
}