#include<iostream>
#include<cassert>
#define rep(i,n) for(i=0;i<(int)(n);i++)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;

int n;
string s;

int main(){
    int i,j;
    scanf("%d",&n);
    cin>>s;
    string ss;
    i=0;
    while(i<n){
        if(s.substr(i,3)=="CPC"){
            ss.push_back('X');
            i+=3;
        }else{
            ss.push_back(s[i]);
            i++;
        }
    }
    i=0;
    j=0;
    while(i<ss.length()){
        if(i+1<ss.length()&&ss[i]=='X'&&ss[i+1]=='T'){
            if(i+2<ss.length()&&(ss[i+2]=='F'||ss[i+2]=='X')){
                j++;
                i+=3;
            }else
                i++;
        }else
            i++;
    }
    printf("%d\n",j);
    return 0;
}