#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
//#include<cctype>
#include<climits>
#include<iostream>
#include<string>
#include<vector>
#include<map>
//#include<list>
#include<queue>
#include<deque>
#include<algorithm>
//#include<numeric>
#include<utility>
#include<complex>
//#include<memory>
#include<functional>
#include<cassert>
#include<set>
#include<stack>

const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, 1, 0, -1};
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef pair<int, int> pii;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int K = 0, U = 0, R = 0, O = 0, I = 0;
    string s;
    cin >> s;
    int n = s.size();
    reverse(s.begin(), s.end());
    for (int i = 0; i < n; i++) {
        switch (s[i]) {
        case 'I':
            I++;
            break;
        case 'O':
            if (I > 0) {
                I--;
                O++;
            }
            break;
        case 'R':
            if (O > 0) {
                O--;
                R++;
            }
            break;
        case 'U':
            if (R > 0) {
                R--;
                U++;
            }
            break;
        case 'K':
            if (U > 0) {
                U--;
                K++;
            }
            break;
        case '?':
            if (U > 0) {
                U--;
                K++;
                break;
            }
            if (R > 0) {
                R--;
                U++;
                break;
            }
            if (O > 0) {
                O--;
                R++;
                break;
            }
            if (I > 0) {
                I--;
                O++;
                break;
            }
            I++;
            break;
            default:
                break;
        }
    }
    cout << K << endl;
    return 0;
}