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

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

		long n = Long.parseLong(br.readLine());
		int big = (int) (n/1000000000);
		int small = (int) (n%1000000000);

		int ans = 0;
		int[] kaibun = new int[110001];
		for(int i=1;i<10;i++){
			kaibun[i] = i;
			kaibun[9+i] = 10*i+i;
		} //20
		for(int i=1; i<10; i++){
			for(int j=0;j<10;j++){
				kaibun[9 + 10*i+j] = 101*i+10*j;
				kaibun[99 + 10*i+j] = 1001*i+110*j;
			}
		}//200
		for(int i=1; i<10; i++){
			for(int j=0;j<10;j++){
				for(int k=0; k<10;k++){
					kaibun[89 + 100*i+10*j+k] = 10001*i+1010*j+100*k ;
					kaibun[989 + 100*i+10*j+k] = 100001*i+10010*j+1100*k;
				}
			}
		}//2000
		for(int i=1; i<10; i++){
			for(int j=0;j<10;j++){
				for(int k=0; k<10;k++){
					for(int l=0;l<10;l++){
						kaibun[889 + 1000*i+100*j+10*k+l] = 1000001*i+100010*j+10100*k+1000*l ;
						kaibun[9889 +1000*i+100*j+10*k+l] = 10000001*i+1000010*j+100100*k+11000*l ;
					}
				}
			}
		}//20000
		for(int i=1; i<10; i++){
			for(int j=0;j<10;j++){
				for(int k=0; k<10;k++){
					for(int l=0;l<10;l++){
						for(int m=0; m<10; m++){
						kaibun[8889 + 10000*i+1000*j+100*k+10*l+m] = 10000001*i+1000010*j+100100*k+101000*l+10000*m ;
						}
					}
				}
			}
		}//110000
		ans = Arrays.binarySearch(kaibun, big);
		if (ans<0){ans = -ans -1;}
		if (Math.abs(Arrays.binarySearch(kaibun, small)) < ans) ans--;
		System.out.println(ans);
	}
}