#include <iostream>
using namespace std;
int main() {
    int n,count = 0;
    cin >> n;
    int arr[n];
    for (int i = 0; i < n; ++i){
        cin >> arr[i];
    }
    for (int i = 0; i < n - 1; ++i) {
        if(arr[i] % 10 + arr[i+1] % 10 < 10){
            ++count;
        }
    }
    cout << count << " ";

    return 0;
}