ll n,a[14],d[2d4];{rd(n,a(n));rep(i,n)rep(j,n)d[1<<i|1<<j]=a[i]^a[j];rep(i,1<<n)rep(j,i)d[i]>?=~i&j?0:d[j]+d[i^j];wt(d[--i]);}