#include <bits/stdc++.h>                                                                     
                                                                                             
using namespace std;                                                                         
                                                                                             
#define all(x) x.begin(), x.end()                                                            
#define rep(i, n) for (int i = 0; i < n; ++i)                                                
#define reps(i, m, n) for (int i = m; i <= n; ++i)                                           
                                                                                             
using i64 = long long;                                                                       
using pii = pair<i64, i64>;                                                                  
                                                                                             
template<class A, class B>inline bool chmax(A &a, const B &b){return b > a ? a = b,1 : 0;}   
template<class A, class B>inline bool chmin(A &a, const B &b){return b < a ? a = b,1 : 0;}   
                                                                                             
constexpr int INF = 0x3f3f3f3f;                                                              
constexpr i64 LINF = 0x3f3f3f3f3f3f3f3fLL;                                                   
constexpr int mod = int(1e9) + 7;                                                            
                                                                                             
int x[110];                                                                                  
                                                                                             
signed main()                                                                                
{                                                                                            
  ios::sync_with_stdio(false);                                                               
  cin.tie(nullptr);                                                                          
                                                                                             
  int n; string s;                                                                           
  cin >> n >> s;                                                                             
                                                                                             
  reps(i, 1, n) {                                                                            
    x[i] = x[i-1];                                                                           
    if (s[i-1] == 'I') x[i]++;                                                               
    else x[i]--;                                                                             
  }                                                                                          
                                                                                             
  sort(x, x + n + 1, greater<int>());                                                        
                                                                                             
  cout << x[0] << "\n";                                                                      
                                                                                             
  return 0;                                                                                  
}                                                                                            

Measured memory_bytes: 384