N=int(input())
A=list(map(int,input().split()))
M=1000
cnt=[0]*M
for a in A:
    cnt[a]+=1
l,r=0,max(A)
def solve(X,cnt):
    if max(cnt)==0:
        retu=[X]
    else:
        retu=[]
        for d in range(M-1,-1,-1):
            if cnt[d]:
                for y in (d,r-d):
                    cnt_=cnt[:]
                    ok=True
                    for x in X:
                        cnt_[abs(x-y)]-=1
                        if cnt_[abs(x-y)]<0:
                            ok=False
                    if ok:
                        retu+=solve(X+[y],cnt_)
                break
    return retu
cnt[r-l]-=1
ans_lst=solve([l,r],cnt)
le=len(ans_lst)
for i in range(le):
    ans_lst[i].sort()
    ans_lst[i]=tuple(ans_lst[i])
ans_lst=list(set(ans_lst))
le=len(ans_lst)
ans_lst.sort()
print(le)
for i in range(le):
    print(*ans_lst[i])