#Aamrun , 11th July 2022

<?php
function F(int $n,int $x,int $y) {
  if ($n == 0) {
    return $x + $y;
  }

  else if ($y == 0) {
    return $x;
  }

  return F($n - 1, F($n, $x, $y - 1), F($n, $x, $y - 1) + $y);
}
echo "F(1,3,3) = " . F(1,3,3);
?>