#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
typedef long long ll;

// 桁数の出力
unsigned GetDigit(unsigned num){
    unsigned digit=0;
    while(num!=0){
        num /= 10;
        digit++;
    }
    return digit;
}

int main() {
    int month = 1;
    int day = 1;
    int ans = 0;
    int a[ 2 ];
    for(int i = 0; i < 31; i++) {
        int digit = GetDigit(day);
        if(digit == 1 && month == day){
            ans++;
        } else if(digit == 2){
            int one = day % 10;
            int two = day / 10;
            if(month == one + two) {
                ans++;
            }
        }

        if(day > 32){
            month++;
            day = 1;
        }
        day++;
    }
    cout << ans << endl;
}