($N,$D,$T)=glob<>;
@X=sort{$a%$D-$b%$D||$a-$b}map$_+1e9,glob<>;
for(@X){
	if( defined$p && $_%$D==$p%$D && ($_/$D|0)-$T<=$m ){
		$%+=($_/$D|0)+$T-$m
	}else{
		$%+=2*$T+1
	}
	$m=($_/$D|0)+$T;
	$p=$_
}
print$%