#include<bits/stdc++.h>
using namespace std;
typedef pair<int,int>P;
typedef vector<int>VI;
#define rep(i,n) for(int i=0;i<(n);i++)
#define pb push_back
#define all(v) (v).begin(),(v).end()
#define maxv(a,b) (a)=max((a),(b))
string kuroi="KUROI";
string s;
VI v;

int dp[2][25][25][25][25];

int main(){
    cin>>s;
    rep(i,s.size()){
        int tmp=-1;
        rep(j,5)if(kuroi[j]==s[i])tmp=j;
        if(~tmp)v.pb(tmp);
        else if(s[i]=='?')v.pb(-1);
    }
    bool b=0;
    memset(dp,-1,sizeof(dp));
    dp[0][0][0][0][0]=0;
    rep(x,v.size()){
        rep(u,21)rep(r,21)rep(o,21)rep(i,21){
            if(dp[b][u][r][o][i]==-1)continue;
            maxv(dp[!b][u][r][o][i],dp[b][u][r][o][i]);
            if(v[x]==0){
                maxv(dp[!b][u+1][r][o][i],dp[b][u][r][o][i]);
            }
            else if(v[x]==1){
                if(u)maxv(dp[!b][u-1][r+1][o][i],dp[b][u][r][o][i]);
            }
            else if(v[x]==2){
                if(r)maxv(dp[!b][u][r-1][o+1][i],dp[b][u][r][o][i]);
            }
            else if(v[x]==3){
                if(o)maxv(dp[!b][u][r][o-1][i+1],dp[b][u][r][o][i]);
            }
            else if(v[x]==4){
                if(i)maxv(dp[!b][u][r][o][i-1],dp[b][u][r][o][i]+1);
            }
            else if(v[x]==-1){
                maxv(dp[!b][u+1][r][o][i],dp[b][u][r][o][i]);
                if(u)maxv(dp[!b][u-1][r+1][o][i],dp[b][u][r][o][i]);
                if(r)maxv(dp[!b][u][r-1][o+1][i],dp[b][u][r][o][i]);
                if(o)maxv(dp[!b][u][r][o-1][i+1],dp[b][u][r][o][i]);
                if(i)maxv(dp[!b][u][r][o][i-1],dp[b][u][r][o][i]+1);
            }
            dp[b][u][r][o][i]=-1;
        }
        b=!b;
    }

    int ans=0;
    rep(u,21)rep(r,21)rep(o,21)rep(i,21)maxv(ans,dp[v.size()&1][u][r][o][i]);
    printf("%d\n",ans);

    return 0;
}