#include <bits/stdc++.h>
using namespace std;
int n;
string s;
int main() {
  cin >> n >> s;
  int sol = n;
  for (int i = 1; i < n; i++) {
    if (s[i] != s[i - 1] and s[i - 1] != 'D') {
      sol--;
      s[i] = 'D';
    }
  }
  cout << sol << endl;
}
