#include <iostream>

using namespace std;

int main(){

   int cnt = 0;

   for(int m = 1; m < 13; m++){
      int days;
      if(m == 2){
         days = 28;
      }
      else if(m == 4 || m == 6 || m == 9 || m == 11){
         days = 30;
      }
      else{
         days = 31;
      }
      
      for(int d = 1; d <= days; d++){
         if(((d / 10) + (d % 10)) == m){
            cnt++;
         }
      }
   }

   cout << cnt << endl;

   return 0;
}