#include<bits/stdc++.h>
using namespace std;
void solve()
{
    string s;
    cin >> s;
    int n = s.length();
    int c = 0, p = 0;
    for(int i = 0; i < n; i++)
    {
        if(s[i] == 'C') c++;
        if(s[i] == 'P') p++;
    }
    int ans = 0;
    if(c)
    {
        c--;
        ans = min(p, c / 2);
    }
    cout << ans << "\n";
}
int main()
{
    cin.tie(0)->sync_with_stdio(false);
    solve();
    return 0;
}