#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define smax(x,y) (x)=max((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()

string S, KUROI = "KUROI";
int N, dp[101][22][22][22][22];

int main(){
    cin >> S;
    N = sz(S);
    MEM(dp, -1);
    dp[0][0][0][0][0] = 0;
    rep(cur, N){
        auto f = [&](){
            rep(k, 21)rep(u, 21)rep(r, 21)rep(o, 21){
                int val = dp[cur][k][u][r][o];
                if(val == -1)continue;
                if(S[cur] == 'K')smax(dp[cur + 1][k + 1][u][r][o], val);
                if(k && S[cur] == 'U')smax(dp[cur + 1][k - 1][u + 1][r][o], val);
                if(u && S[cur] == 'R')smax(dp[cur + 1][k][u - 1][r + 1][o], val);
                if(r && S[cur] == 'O')smax(dp[cur + 1][k][u][r - 1][o + 1], val);
                if(o && S[cur] == 'I')smax(dp[cur + 1][k][u][r][o - 1], val + 1);
                smax(dp[cur + 1][k][u][r][o], val);
            }
        };
        if(S[cur] == '?'){
            each(c, KUROI){
                S[cur] = c;
                f();
            }
        } else{
            f();
        }
    }
    int ans = 0;
    rep(k, 21)rep(u, 21)rep(r, 21)rep(o, 21)smax(ans, dp[N][k][u][r][o]);
    cout << ans << endl;
}