#include <iostream>

using namespace std;
const int N=105;
int n;
char g[N];
int res;
int main()
{
    cin>>n;
    cin>>g;

    for(int i=0;i<n-2;i++){
        if(g[i]!='x') continue;
        int j=i+1;
        while(j<n&&g[j]=='x') j++;
        if(j-i>2) res+=j-i-2;//r若有连续的
        i=j-1;
    }
    cout<<res;
    //cout << "Hello world!" << endl;
    return 0;
}