#include "bits/stdc++.h"
using namespace std;
#define int long long
const int MAXN = 3e5 + 10;
const int MOD = 1e9 + 7;
mt19937_64 rng((int)std::chrono::steady_clock::now().time_since_epoch().count());
int rnd(int x, int y) {
int u = uniform_int_distribution<int>(x, y)(rng); return u;
}
int bm(int b, int p) {
if(p==0) return 1 % MOD;
int r = bm(b, p >> 1);
if(p&1) return (((r*r) % MOD) * b) % MOD;
return (r*r) % MOD;
}
int inv(int b) {
return bm(b, MOD-2);
}
int fastlog(int x) {
return (x == 0 ? -1 : 64 - __builtin_clzll(x) - 1);
}
void printcase(int i) { cout << "Case #" << i << ": "; }
int prej[MAXN];
int prejo[MAXN];
int sufi[MAXN];
int sufoi[MAXN];
int joi[MAXN];
void solve(int tc) {
int n;
cin >> n;
char c[n+1];
for(int i=1; i<=n; i++) cin >> c[i];
for(int i=1; i<=n; i++) {
prej[i] = prej[i-1] + (c[i] == 'J');
prejo[i] = prejo[i-1] + (c[i] == 'O' ? prej[i-1] : 0);
joi[i] = joi[i-1] + (c[i] == 'I' ? prejo[i-1] : 0);
}
for(int i=n; i>=1; i--) {
sufi[i] = sufi[i+1] + (c[i] == 'I');
sufoi[i] = sufoi[i+1] + (c[i] == 'O' ? sufi[i+1] : 0);
}
int ans = max(sufoi[1], prejo[n]);
for(int i=1; i<n; i++) {
ans = max(ans, prejo[i]);
ans = max(ans, prej[i] * sufi[i+1]);
ans = max(ans, sufoi[i+1]);
}
cout << ans + joi[n] << '\n';
}
int32_t main() {
ios::sync_with_stdio(0); cin.tie(0);
int t = 1; //cin >> t;
for(int i=1; i<=t; i++) solve(i);
}
// 勿忘初衷
