#include <bits/stdc++.h>
#define rep(i,a,b) for (auto i = (a); i <= (b); ++i)
#define per(i,a,b) for (auto i = (b); i >= (a); --i)
#define all(x) begin(x),end(x)
#define siz(x) int((x).size())
#define Mup(x,y) x = max(x,y)
#define mup(x,y) x = min(x,y)
#define dbg(...) fprintf(stdout,__VA_ARGS__)
#define fi first
#define se second
using namespace std; using ll = long long; using ii = pair<int,int>;
const int N = 1e5+3;
int n;
char s[N];
ll ans, diff;
ll cJ[N], cI[N];
ll cJO[N], cOI[N];
int main() {
cin.tie(0)->sync_with_stdio(0);
// 지문이 너무 난해하다..
// 조합.. 든든하군
cin >> n >> &s[1];
rep(i,1,n) cJ[i] = cJ[i-1]+(s[i]=='J');
per(i,1,n) cI[i] = cI[i+1]+(s[i]=='I');
rep(i,1,n) if (s[i]=='O') ans += cJ[i-1]*cI[i+1];
rep(i,1,n) {
cJO[i] = cJO[i-1];
if (s[i]=='O') cJO[i] += cJ[i-1];
}
per(i,1,n) {
cOI[i] = cOI[i+1];
if (s[i]=='O') cOI[i] += cI[i+1];
}
rep(i,0,n) {
// between i and i+1
// select 'J'
Mup(diff, cOI[i+1]);
// select 'O'
Mup(diff, cJ[i]*cI[i+1]);
// select 'I'
Mup(diff, cJO[i]);
}
cout << ans+diff;
}
