#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2,fma")
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
#define MAX 201010
#define MAXS 20
#define INF 1000000000000000001
#define bb ' '
#define ln '\n'
#define Ln '\n'
int arr[MAX];
ll pj[MAX];
ll pjo[MAX];
ll si[MAX];
ll soi[MAX];
signed main() {
ios::sync_with_stdio(false), cin.tie(0);
int N;
cin >> N;
string s;
cin >> s;
int i;
for (i = 1; i <= N; i++) if (s[i - 1] != 'J') arr[i] = s[i - 1] == 'O' ? 1 : 2;
for (i = 1; i <= N; i++) {
if (!arr[i]) pj[i] = 1;
pj[i] += pj[i - 1];
if (arr[i] == 1) pjo[i] += pj[i - 1];
pjo[i] += pjo[i - 1];
}
for (i = N; i >= 1; i--) {
if (arr[i] == 2) si[i] = 1;
si[i] += si[i + 1];
if (arr[i] == 1) soi[i] += si[i + 1];
soi[i] += soi[i + 1];
}
ll ans = 0;
for (i = 1; i <= N; i++) if (arr[i] == 1) ans += pj[i] * si[i];
ll mx = 0;
for (i = 1; i < N; i++) mx = max(mx, pj[i] * si[i + 1]);
mx = max(mx, soi[1]);
mx = max(mx, pjo[N]);
cout << ans + mx << ln;
}
