#include <bits/stdc++.h>
using namespace std;
 
int n;
string s;
int r = 0,c = 0;
int main() {
    cin>>n>>s;
    for(int i = 0;i < n;i++){
        if(s[i] == 'V') r++;
        else if(s[i] == 'X') r--;
        //统计连胜的情况
        if(s[i]=='V'){
            c++;
            if(c >= 3) r++;
            //连胜结束 
            if(i==n-1||s[i+1]!='V'){
                c = 0; 
            } 
        } 
    }
     
    cout<<r;
}
 
/**************************************************************
	Problem: 2002
	User: admin
	Language: C++
	Result: Accepted
	Time:51 ms
	Memory:2076 kb
****************************************************************/