• 双指针暴力即可

#include<iostream>
using namespace std;
int main()
{
    int n;cin>>n;
    string a;cin>>a;
    int l=0,r=1;
    int ans=0;
    while(l<n&&r<n)
    {
        if(a[l]=='x'&&a[r]=='x'&&l<n&&r<n)r++;
        while(a[l]=='x'&&a[r]=='x'&&l<n&&r<n)r++,ans++;
        if(l>=n||r>=n)break;
        if(a[r]!='x'&&l<n&&r<n)l=r;
        while(a[l]!='x'&&l<n&&r<n)l++;
        r=l+1;
    }
    cout<<ans<<endl;
    return 0;
}
//2021-19:14