#include <cassert>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <iomanip>
#include <climits>
#include <map>
#include <queue>
#include <set>
#include <cstring>
#include <vector>

using namespace std;
typedef long long ll;

int dp[110][21][21][21][21];

int main() {
  string S;
  cin >> S;
  int N = S.size();

  memset(dp, -1, sizeof(dp));
  dp[0][0][0][0][0] = 0;
  int ans = 0;

  for (int i = 0; i < N; ++i) {
    char ch = S[i];
    if (i > 0) {
      memcpy(dp[i + 1], dp[i], sizeof(dp[i]));
    }

    for (int k = 0; k <= 20; ++k) {
      for (int u = 0; u <= 20; ++u) {
        for (int r = 0; r <= 20; ++r) {
          for (int o = 0; o <= 20; ++o) {
            int cnt = dp[i][o][r][u][k];
            if (cnt < 0) continue;

            if ((ch == 'K' || ch == '?') && k < 20) {
              dp[i + 1][o][r][u][k + 1] = max(dp[i + 1][o][r][u][k + 1], cnt);
            }
            if ((ch == 'U' || ch == '?') && u < 20 && k > 0) {
              dp[i + 1][o][r][u + 1][k - 1] = max(dp[i + 1][o][r][u + 1][k - 1], cnt);
            }
            if ((ch == 'R' || ch == '?') && r < 20 && u > 0) {
              dp[i + 1][o][r + 1][u - 1][k] = max(dp[i + 1][o][r + 1][u - 1][k], cnt);
            }
            if ((ch == 'O' || ch == '?') && o < 20 && r > 0) {
              dp[i + 1][o + 1][r - 1][u][k] = max(dp[i + 1][o + 1][r - 1][u][k], cnt);
            }
            if ((ch == 'I' || ch == '?') && o > 0) {
              ans = max(ans, cnt + 1);
              dp[i + 1][o - 1][r][u][k] = max(dp[i + 1][o - 1][r][u][k], cnt + 1);
            }
          }
        }
      }
    }
  }

  cout << ans << endl;

  return 0;
}