#include <iostream>
#include <vector>
using namespace std;
int main()
{
  char ans;
  ans='T';
  int t;
  cin>>t;
  vector<int> x(t+1);
  x[0]=0;
  for(int i=1;i<=t;i++){
    cin>>x[i];
    if(x[i]!=x[i-1]+1&&x[i]!=x[i-1]-1){
      ans='F';
      break;
    }
  }
  cout<<ans<<endl;
}