<?php
$count = trim(fgets(STDIN));
$array = array();
for ($i = 0; $i < $count; $i++) {
    $array[] = trim(fgets(STDIN));
}
$cnt = 0;
for ($i = 0; $i < $count-1; $i++){
    if (abs($array[$i] - $array[$i+1]) == 1) {
        $cnt++;
    }
}
if ($cnt == count($array) - 1 && $array[0] != 0 && count($array) >= 2) {
    echo "T";
} else {
    echo "F";
}