#include <bits/stdc++.h>
using namespace std;
#define int long long
#define INF (int)1e18
#define f first
#define s second
mt19937_64 RNG(chrono::steady_clock::now().time_since_epoch().count());
void Solve()
{
int n; cin >> n;
string s; cin >> s;
vector <int> a(n + 1);
for (int i = 1; i <= n; i++){
if (s[i - 1] == 'J') a[i] = 1;
else if (s[i - 1] == 'O') a[i] = 2;
else a[i] = 3;
}
vector<vector<int>> dp(n + 1, vector<int>(4, 0));
dp[0][0] = 1;
for (int i = 1; i <= n; i++){
for (int j = 0; j <= 3; j++){
dp[i][j] += dp[i - 1][j];
if (a[i] == j + 1) dp[i][j + 1] += dp[i - 1][j];
}
}
int add = dp[n][3];
int ans = 0;
int c1 = 0, c2 = 0;
for (int i = 1; i <= n; i++){
if (a[i] == 2){
c1++;
} else if (a[i] == 3) c2 += c1;
}
ans = max(ans, c2);
c1 = 0, c2 = 0;
for (int i = n; i >= 1; i--){
if (a[i] == 2){
c1++;
} else if (a[i] == 1) c2 += c1;
}
ans = max(ans, c2);
int a1 = 0, a2 = 0;
for (int i = 1; i <= n; i++){
a1 += a[i] == 3;
}
for (int i = 1; i <= n; i++){
a2 += a[i] == 1;
a1 -= a[i] == 3;
ans = max(ans, a1 * a2);
}
// cout << add << "\n";
cout << ans + add << "\n";
}
int32_t main()
{
auto begin = std::chrono::high_resolution_clock::now();
ios_base::sync_with_stdio(0);
cin.tie(0);
int t = 1;
// cin >> t;
for(int i = 1; i <= t; i++)
{
//cout << "Case #" << i << ": ";
Solve();
}
auto end = std::chrono::high_resolution_clock::now();
auto elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin);
cerr << "Time measured: " << elapsed.count() * 1e-9 << " seconds.\n";
return 0;
}
