#include <bits/stdc++.h>
using namespace std;

int get_digit(long num){
	int digit = 0;
	while(num != 0){
		num /= 10;
		digit++;
	}
	return digit;
}

long get_3times_number(long num){
    int digit = get_digit(num);
    long x = 1;
    for(int i=0;i<digit;i++){
        x = x*10;
    }
    return (num*x*x + num*x + num);
}

int main(){
    long N;
    scanf("%ld",&N);
    long times_num = 111;
    long i = 1;
    while(times_num <= N){
        i++;
        times_num = get_3times_number(i);
    };
    printf("%ld",i);
}