#include<iostream>
#include<cstdio>
#include<algorithm>
#include<vector>
#include<set>
#include<map>
#include<functional>
#include<string>
#include<cstring>
#include<cstdlib>
#include<queue>
#include<utility>
#include<fstream>
#include<sstream>
#include<cmath>
#include<stack>
#include<assert.h>
using namespace std;

#define f(i,a,b) for(int i = a;i < b;i++)
#define pb push_back
#define itr iterator
#define get(t) int t;cin >> t;
#define fi first
#define se second
#define mp make_pair
#define foreach(it,x) for(__typeof(x.begin()) it=x.begin();it!=x.end(); it++)
#define all(x) x.begin(),x.end()


typedef long long ll;
typedef vector<int> vi;
typedef vector<vector<int> > vii;
typedef vector<double> vd;

inline void sfr (int *a)
{
    char c = 0;
    while(c<33)
    c = fgetc(stdin);
    *a = 0;
    while(c>33)
    {
               *a = *a*10 + c - '0';
               c = fgetc(stdin);
    }
}

inline void sfp(int a){
     char c[1000];
     sprintf(c,"%d",a);
     puts(c);
}

char s[100000], st[100000];
int n, i, sp, ret, kol[5], t;

int subtask1(string s){
    n = s.length();
    vector<int> A(n,0);
    int cnt = 0;
    f(i,0,n){
             if(s[i] == 'F'){
                     vector<int> P;
                     P.pb(i);
                     int st = 1;
                     for(int j = i-1;j >= 0;j--){
                             if(st == 1 && s[j] == 'E' && A[j] == 0){
                                   st++;
                                   P.pb(j);
                             }
                             if(st == 2 && s[j] == 'H' && A[j] == 0){
                                   st++;
                                   P.pb(j);
                             }
                             if(st == 3 && s[j] == 'C' && A[j] == 0){
                                   st++;
                                   P.pb(j);
                                   break;
                             }
                     }
                     if(st == 4){
                           cnt++;
                           f(i,0,P.size()){
                                           A[P[i]] = 1;
                           }
                     }
             }
    }
    return cnt;
}

int subtask2(string s){
    kol[0] = n + 1;
	for(i = 0; i < n; i++) {
		if (s[i] == 'C') t = 1; else
		if (s[i] == 'H') t = 2; else 
		if (s[i] == 'E') t = 3; else 
		if (s[i] == 'F') t = 4; else t = 0;
		if (!t) continue;
		if (kol[t - 1]) {
			--kol[t - 1];
			++kol[t];
		}
	}
	return kol[4];
}

int main(){
    string s;
    cin >> s;
    if(s.length() <= 2000){
                  cout << subtask1(s) << endl;
    }
    else cout << subtask2(s) << endl;
    
}