#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define trav(a, x) for(auto& a : x)
#define FOR(i, a, b) for (int i=(a); i<=(signed)(b); i++)
#define ROF(i, a, b) for (int i=(a); i>=(signed)(b); i--)
#define F0R(i, a) for (int i=0; i<(signed)(a); i++)
#define vi vector<int>
#define f first
#define s second
#define all(v) (v).begin(), (v).end()
typedef long long ll;

using P = pair<int, int>;

const ll mod = 998244353;

const char c[] = {'P', 'E', 'R'};

int main() 
{	
    ios_base::sync_with_stdio(0); cin.tie(0);
    string s; cin >> s;
    int ans = 0;
    F0R(i, s.size()) {
        if(s[i] != c[i%3]) ans++;
    }
    cout << ans << '\n';
    return 0;
}