use strict;
#------------------------------------------------------
sub a {
    my ($n)=@_;

    my @cash;
    $cash[1]=1;

    for(my $i = 2 ; $i <= $n; $i++)
    {
       $cash[$i]=$i - $cash[$cash[$i-1]];
    }

    return($cash[$n]);
}
#------------------------------------------------------
sub main {
    print a(50000000),"\n";
}
#------------------------------------------------------
main(@ARGV);