#include <bits/stdc++.h>
#define rep(i, n) for (int i = 1; i <= (n); i++)
using namespace std;
typedef long long ll;

int main(){
    int cnt = 0;
    rep(i,12)rep(j, 31){
        int x = j % 10, y = (j - x) / 10;
        if(i == x + y){
            cnt++;
        }
        if(i == 4 || i == 6 || i == 9  || i == 11){
            if(j == 30){
                break;
            }
        }
        if(i == 2){
            if(j == 28){
             break;
            }
        }
    }

    cout << cnt << endl;
    return 0;
}