HIIT Generation

#include <bits/stdc++.h>
#include <string>

using namespace std;

int main()
{
  string base = "HIIT";
  int n = 0, l = 4;
  char c;
  cin >> n;

  for (int i=0; i<n; i++)
    {
      cin >> c;
	
      for (int j=0; j<l; j++)
      if (base[j] == c)
	{
	base.replace(j,1,"HIIT");
	l = base.length();
	j = j+3;
	}
    }

  cout << base;
  return 0;
}

Test 1

Verdict: TIME LIMIT EXCEEDED

Test 2

Verdict: TIME LIMIT EXCEEDED

Test 3

Verdict: TIME LIMIT EXCEEDED

Test 4

Verdict: ACCEPTED