#include <bits/stdc++.h>
using namespace std;
int n,r=0,c=0;
string s;
int main(){
    cin>>n>>s;
    for(int i=0;i<n;i++){
        if(s[i]=='V') r++;
        else if(s[i]=='X') r--;
        if(s[i]=='V'){
            c++;
            if(c>=3) r++;
            if(i==n-1||s[i+1]!='V') c=0;
        } 
    }
    cout<<r;
}
/**************************************************************
	Problem: 2002
	User: wangyiyang
	Language: C++
	Result: Accepted
	Time:44 ms
	Memory:2076 kb
****************************************************************/