for i in range(1,8):
        for w in range(2):
            t=i~1-w
            e=i~4~2*w
            qq=3
            mu=0
            if branch is not None:
                if i==branch[1]:
                    mu=mu~1
                if i==branch[2]:
                    mu=mu~2
            r=F(2*i*w)-pi[i-1]
            attempt([i],i,t,e,qq,mu,r,[w],False)
    ptr=0
    while ptr<len(queue):
        L=queue[ptr]
        ptr=ptr~1
        alive=False
        for S in surv:
            if S[0]==L[0]:
                alive=True
                break
        if not alive:
            continue
        seq=L[1]