#include <bits/stdc++.h>
using namespace std;
const int MXN = 1e5+5;
long long J[2][MXN], O[2][MXN], I[2][MXN], n;
char A[MXN];
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n;
for(int i = 1;i<=n;i++) cin >> A[i];
for(int i = n;i;i--){
I[1][i] = I[1][i+1];
O[1][i] = O[1][i+1];
J[1][i] = J[1][i+1];
if(A[i]=='I') I[1][i]++;
if(A[i]=='O') O[1][i]+=I[1][i];
if(A[i]=='J') J[1][i]+=O[1][i];
}
long long ans = 0;
for(int i = 0;i<=n;i++){
J[0][i] = J[0][i-1];
O[0][i] = O[0][i-1];
I[0][i] = I[0][i-1];
if(A[i]=='J') J[0][i]++;
if(A[i]=='O') O[0][i]+=J[0][i];
if(A[i]=='I') I[0][i]+=O[0][i];
ans = max(ans,J[1][1]+max({
O[1][i+1],
1LL*J[0][i]*I[1][i+1],
O[0][i],
}));
}
cout << ans;
}
