#include<bits/stdc++.h>
using namespace std;
char a[1000000];
int b[1000000];
int main()
{
	int n;
	cin >> n;
	for(int i = 1; i <= n; i++){
		cin >> a[i];
	}	
	int sum = 0, k = 0;
	/*
	8
	VVVTTXVV
	3+1 -1 + 2 = 5
	*/
	for(int i = 1; i <= n; i++){
		if(a[i] == 'V'){
			k++;
			sum++;
		}
		if(i == n || a[i+1] != 'V'){
			if(k >= 3){
				sum = sum + k-2;
			}
			k = 0;
		}
		if(a[i] == 'X'){
			sum--;
		}
	}
	cout << sum;
	return 0;
}