#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cctype>
#include<cstdlib>
#include<algorithm>
#include<bitset>
#include<vector>
#include<list>
#include<deque>
#include<queue>
#include<map>
#include<set>
#include<stack>
#include<cmath>
#include<sstream>
#include<fstream>
#include<iomanip>
#include<ctime>
#include<complex>
#include<functional>
#include<climits>
#include<cassert>
#include<iterator>
using namespace std;

string s;
int dp[102][25][25][25][25];
bool use[102][25][25][25][25];
int main() {
	cin >> s;
	int ans = 0;
	use[0][0][0][0][0] = true;
	for (int i = 0;i < s.size();i++) {
		for (int j = 0;j <= 20;j++) {
			for (int k = 0;k <= 20;k++) {
				for (int kk = 0;kk <= 20;kk++) {
					for (int kkk = 0;kkk <= 20;kkk++) {
						if (use[i][j][k][kk][kkk]) {
						//	cout << j << " " << k << " " << kk << " " << kkk << endl;
							dp[i + 1][j][k][kk][kkk] = max(dp[i + 1][j][k][kk][kkk], dp[i][j][k][kk][kkk]);
							use[i + 1][j][k][kk][kkk] = true;
							if (s[i] == 'K'||s[i]=='?') {
								if (j+ 1 <= 25) {
									dp[i + 1][j + 1][k][kk][kkk] = max(dp[i + 1][j + 1][k][kk][kkk], dp[i][j][k][kk][kkk]);
									use[i + 1][j + 1][k][kk][kkk] = true;
									//continue;
								}
							}
							int mint = j;
							if (s[i] == 'U' || s[i] == '?') {
								if (min(mint,k + 1) <= 25) {
									dp[i + 1][j][min(mint,k+1)][kk][kkk] = max(dp[i + 1][j][min(mint,k+1)][kk][kkk], dp[i][j][k][kk][kkk]);
									use[i + 1][j][min(mint,k + 1)][kk][kkk] = true;
									//continue;
								}
							}
							mint = min(mint, k);
							if (s[i] == 'R' || s[i] == '?') {
								if (kk + 1 <= 25) {
									dp[i + 1][j][k][min(mint,kk+1)][kkk] = max(dp[i + 1][j][k][min(kk+1,mint)][kkk], dp[i][j][k][kk][kkk]);
									use[i + 1][j][k][min(mint,kk + 1)][kkk] = true;
								//	continue;
								}
							}
							mint = min(mint, kk);
							if (s[i] == 'O' || s[i] == '?') {
								if (min(mint,kkk + 1) <= 25) {
									dp[i + 1][j][k][kk][min(mint,kkk+1)] = max(dp[i + 1][j][k][kk][min(mint,kkk+1)], dp[i][j][k][kk][kkk]);
									use[i + 1][j][k][kk][min(mint,kkk + 1)] = true;
								//	continue;
								}
							}
							mint = min(mint, kkk);
							if (s[i] == 'I' || s[i] == '?') {
								if (j&&k&&kk&&kkk) {
									dp[i + 1][j-1][k-1][kk-1][kkk-1] = max(dp[i + 1][j-1][k-1][kk-1][kkk-1], dp[i][j][k][kk][kkk] + 1);
									ans = max(ans, dp[i + 1][j-1][k-1][kk-1][kkk-1]);
									use[i + 1][j-1][k-1][kk-1][kkk-1] = true;
								}
							}
						}
					}
				}
			}
		}
	}
	cout << ans << endl;
	return 0;
}