#include <iostream>
using namespace std;
#define chmax(p,q) (p<q?p=q:p)
int dp[101][22][22][22][22];

main() {
    string s;
    cin>>s;
    int ans=1;
    dp[0][0][0][0][0]=1;
    for (int i=0;i<s.size();++i) {
        for (int K=0;K<=20;++K) {
            for (int U=0;U<=K;++U) {
                for (int R=0;R<=U;++R) {
                    for (int O=0;O<=R;++O) {
                        int src=dp[i][K][U][R][O];
                        if (src!=0) {
                            char c=s[i];
                            if (c=='K' || c=='?')
                                chmax(dp[i+1][K+1][U][R][O],src);
                            if (c=='U' || c=='?') 
                                chmax(dp[i+1][K][U+1][R][O],src);
                            if (c=='R' || c=='?')
                                chmax(dp[i+1][K][U][R+1][O],src);
                            if (c=='O' || c=='?')
                                chmax(dp[i+1][K][U][R][O+1],src);
                            if (c=='I' || c=='?') if (O>src-1) {
                                chmax(dp[i+1][K][U][R][O],src+1);
                                ans=max(ans,dp[i+1][K][U][R][O]);
                            }
                            chmax(dp[i+1][K][U][R][O],dp[i][K][U][R][O]);
                        }
                    }
                }
            }
        }
    }
    cout<<ans-1<<endl;
}