#include<bits/stdc++.h>
using namespace std;
#define pii pair<int,int>
#define ll long long
#define inf 0x3f3f3f3f
#define ull unsigned long long
#define pll pair<ll,ll>
#define ls d*2
#define rs d*2+1
#define mid (l+r)/2
#define lowbit(x) (x&(-x))
//#define endl "\n"
#define all(x) x.begin(),x.end()
#define int long long
//mt19937 seed;
//uniform_int_distribution<int>num(0,2e9);
const int N=1e6+10;
const int M=33;



signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    int _=1;//cin>>_;
    while(_--){
        string s;
		cin>>s;
		int cnt1=0,cnt2=0;
		int n=s.length();
		for(int i=0;i<n;i++)cnt1+=(s[i]=='C'),cnt2+=(s[i]=='P');
		cout<<min(cnt1/3,cnt2)<<endl;
    }
}