#![allow(dead_code, unused_mut)]
#![allow(non_snake_case)]

macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let mut s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};

    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };

    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };

    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };

    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };

    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}

fn main() {
    input!{
        n:usize
    }
    let d = vec![0, 3, 6, 9];
    let mut ans = 0;
    for i in 10..std::cmp::min(100, n+1) {
        if i % 3 == 0 && (i / 10 % 3 + i % 10 % 3) == 3 {
            ans += 1;
        }
    }
    let mut dp = vec![vec![0; 2]; 11];
    dp[10][1] = 1;
    for i in (0..10).rev() {
        let v = n / 10usize.pow(i as u32) % 10;
        for &j in &d {
            if j < v {
                dp[i][0] += dp[i+1][1] + dp[i+1][0];
            } else if j == v {
                dp[i][0] += dp[i+1][0];
                dp[i][1] += dp[i+1][1];
            } else {
                dp[i][0] += dp[i+1][0];
            }
        }

    }
    // println!("{:?}", dp);
    println!("{}", ans + dp[0][0] + dp[0][1] - 4);
}