#include <bits/stdc++.h>
using namespace std;
int main(int argc, char const *argv[]) {
  int n;
  cin >> n;
  string s;
  cin >> s;
  int res = 0;
  for (int i = 0; i < n; ++i) {
    if (i < n - 1 && s[i] != s[i + 1]) i++;
    res++;
  }
  cout << res << endl;
  return 0;
}
