#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

int main()
{
    int n;
    string s;
    cin >> n >> s;
    int res = 0;
    for (int i = 0; i < n; i ++ )
    {
        if (s[i] != 'x') continue;
        int j = i + 1;
        while (j < n && s[j] == 'x') j ++ ;
        res += max(0, j - i - 2);
        i = j - 1;
    }
    cout << res << endl;
    return 0;
}