r[1<<24];main(){
	int m[24][24],n,i,j,k,t,s;
	scanf("%d",&n);
	for(i=0;i<n;i++)for(j=0;j<n;j++)scanf("%d",m[i]+j);
	for(i=0;i<1<<n;i++)if(!__builtin_parity(i))for(j=0;j<n;j++)if(!(i&1<<j))for(k=0;k<j;k++)if(!(i&1<<k))if(t=i|1<<j|1<<k,s=r[i]+m[j][k],r[t]<s)r[t]=s;
	printf("%d\n",r[(1<<n)-1]);
}