my $count = 0;
my $lastCount = 0;
my $totalValleys = 0;
my $line1 = <>;
my $line2 = <>;

@steps = split('', $line2);

foreach (@steps) {
 s/U/\+1\n/g;
 s/D/\-1\n/g;
 $lastCount = $count;
 $count = $count + $_;
 if ( $count == 0 and $lastCount < 0 ) {
   $totalValleys++;
 }
}

print $totalValleys;