#include <bits/stdc++.h> using namespace std; const int N = 222222; string s; map<int, map<int, map<int, int>>> mp; int n, J, O, I, ans; signed main(){ ios_base::sync_with_stdio(false); cin.tie(NULL); cin >> n >> s; s = " " + s; for(int i = 1;i<=n;i++){ J += (s[i] == 'J'); O += (s[i] == 'O'); I += (s[i] == 'I'); if(J == O && O == I){ ans = max(ans, i); }else if(mp[J - O][O - I][J - I] == 0){ mp[J - O][O - I][J - I] = i; }else{ ans = max(ans, i - mp[J - O][O - I][J - I]); } } cout << ans; }