#include <bits/stdc++.h>

using i64 = long long;
using u64 = unsigned long long;
using u32 = unsigned;
using u128 = unsigned __int128;

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    std::string S;
    std::cin >> S;
    
    int C = 0, P = 0;
    for (auto c : S) {
        if (c == 'C') {
            C++;
        }
        if (c == 'P') {
            P++;
        }
    }
    
    int ans = std::min((C - 1) / 2, P);
    std::cout << ans << "\n";
    
    return 0;
}