#include <iostream>
using namespace std;
#define ll long long
ll J[100005], O[100005], I[100005];
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
int n; string s;
cin >> n >> s;
ll org = 0;
for(int i = 0; i < n; i++)
{
J[i+1] = J[i];
if(s[i] == 'J')
J[i+1]++;
}
for(int i = 0; i < n; i++)
{
O[i+1] = O[i];
if(s[i] == 'O')
O[i+1] += J[i+1];
}
for(int i = 0; i < n; i++)
{
I[i+1] = I[i];
if(s[i] == 'I')
I[i+1] += O[i+1];
}
org = I[n];
ll ans = org;
for(int i = 1; i <= n; i++)
ans = max(ans, org + O[i]);
fill(O, O+n+1, 0);
fill(I, I+n+1, 0);
for(int i = n-1; i >= 0; i--)
{
I[i] = I[i+1];
if(s[i] == 'I')
I[i]++;
}
for(int i = n-1; i >= 0; i--)
{
O[i] = O[i+1];
if(s[i] == 'O')
O[i] += I[i];
}
for(int i = 0; i < n; i++)
ans = max(ans, org + O[i]);
fill(J, J+n+1, 0);
fill(I, I+n+1, 0);
for(int i = 0; i < n; i++)
{
J[i+1] = J[i], I[i+1] = I[i];
if(s[i] == 'J')
J[i+1]++;
else if(s[i] == 'I')
I[i+1]++;
}
for(int i = 1; i < n; i++)
ans = max(ans, org + J[i]*(I[n]-I[i]));
cout << ans << '\n';
}
