#include <bits/stdc++.h>
using namespace std;
const set<set<string>> correct = {{"lu", "ru"}, {"ld", "rd"}};
int main() {
  int n, i, r;
  string x, y;
  for (; cin >> n, n; cout << r << endl) {
    for (r = i = 0; i < n / 2; i++) {
      set<string> se;
      cin >> x >> y;
      se.insert(x);
      se.insert(y);
      if (correct.find(se) != correct.end()) r++;
    }
    if (n & 1) cin >> x;
  }
}
