#!/usr/bin/env perl

use strict;
use utf8;
use warnings;

my $t = <>;
my $p = 0;
for (1...$t) {
  my $x = <>; chomp $x;
  if (abs($p - $x) != 1) {
    print "F\n";
    exit;
  }
  $p = $x;
}
print "T\n";