boj_1065.java

package brute_force;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class boj_1065 {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int N = Integer.parseInt(br.readLine());

        System.out.println(NumberCount(N));
    }

    private static int NumberCount(int N) {

        int cnt = 0;

        if(N<100) {
            return N;
        } else {
            cnt = 99;

            for(int i=100; i<=N; i++) {

                int A = i / 100;
                int B = (i / 10) % 10;
                int C = i % 10;

                if(B-A == C-B) {
                    cnt++;
                }
            }
        }
        return cnt;
    }
}