ll@n,@q,@a[n],c[],@b[q];
rep(i,n){
	c[i]=i;
}
rep(j,q){
	ll w=ll_inf;
	rep(i,n){
		w<?=c[i];
		c[i]=w;
		w+=1;
	}
	w=ll_inf;
	rrep(i,n){
		w<?=c[i];
		c[i]=a[i]==b[j]?w:ll_inf;
		w+=1;
	}
}
wt(min(c(n)));