N,*T=$<.map{|s|s.split.map &:to_i}
d={}
g=->u{d[u]||=(0...a=u.bit_length-1).map{|b|u[b]>0?T[a][b]+g[1<<b|1<<a^u]:0}.max||0}
p g[~(-1<<N[0])]