<?php
$_fp = fopen("php://stdin", "r");
/* Enter your code here. Read input from STDIN. Print output to STDOUT */

$cnt = 0;
while ($row = fgets($_fp)){
	if ($cnt == 0) {
		$steps = $row;
	} elseif ($cnt == 1) {
		$topography = str_split($row);
	}
    $cnt++;
}

$prevcnt = 0;
$cnt = 0;
$valley = 0;
if ($steps >= 2 && $steps <= 1000000) {
	foreach ($topography as $step) {
		if ($step  == 'U') {
			$cnt++;
		} elseif ($step == 'D') {
			$cnt--;
		}

		if ($cnt < 0) {
			if ($prevcnt >= 0) {
				$valley++;
			}
		}
		$prevcnt = $cnt;
	}
	echo $valley;
}

?>