#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

#define rd_init() char*rp=({char*mmap();mmap(0l,1l<<25,1,2,0,0ll);})
#define rd() ({int _v=0,_c;while(_c=*rp++-48,_c>=0)_v=_v*10+_c;_v;})
#define wt(v) ({unsigned _z=v;do*--wp=_z%10+48;while(_z/=10);})
#define wt1(v) ({char wbuf[64],*wp=wbuf+sizeof wbuf;wt(v);write(1,wp,wbuf+sizeof wbuf-wp);})
#define rep(v,e) for(typeof(e) v=0;v<e;++v)
#define rrep(v,e) for(typeof(e) v=e;v--;)
#define chmin(v,a) (v=v<=a?v:a)

int a[1000];
int c[1000];

int main(){
	rd_init();
	int n=rd();
	int q=rd();
	rep(i,n){
		a[i]=rd();
		c[i]=i;
	}
	rep(j,q){
		int b=rd();
		int w=1<<30;
		rep(i,n){
			chmin(w,c[i]);
			c[i]=w;
			w+=1;
		}
		w=1<<30;
		rrep(i,n){
			chmin(w,c[i]);
			c[i]=a[i]==b?w:1<<30;
			w+=1;
		}
	}
	int z=1<<30;
	rep(i,n){
		chmin(z,c[i]);
	}
	wt1(z);
	_exit(0);
}