Problem:
There are N integers, A_1, A_2, ..., A_N, written on a blackboard.  We will repeat the following operation N-1 times so that we have only one integer on the blackboard.    * Choose two integers x and y on the blackboard and erase these two integers. Then, write a new integer x-y.  Find the maximum possible value of the final integer on the blackboard and a sequence of operations that maximizes the final integer.

Incorrect submission (verdict: Wrong Answer):
n=int(input())
newlist = list(map(int, input().split()))

switch=0
mazu=newlist[0]

for nl in newlist:
    if mazu!=nl:
        switch=1

if switch==1:
    wa=0
    for nl in newlist:
        wa+=abs(nl)
    print(wa)
else:
    print(mazu*(len(newlist)-2))

Fixed, accepted submission:
n=int(input())
newlist = list(map(int, input().split()))

switch=0
counter=0
mazu=newlist[0]
if newlist[0]>=0:
    seihu=1
else:
    seihu=-1
konzai=0

for nl in newlist:
    if mazu!=nl:
        switch=1

if switch==1:
    wa=0
    list2=[]
    for nl in range(n):
        list2.append([newlist[nl], abs(newlist[nl])])
        if seihu*newlist[nl]<0:
            konzai=1
            numb=nl
            numba=newlist[numb]
    if konzai==1:
        wa=0
        for nl in range(n):
            wa+=abs(newlist[nl])
        print(wa)
        now=newlist[numb]
        #print(newlist)
        newlist.remove(numba)
        #print(newlist)
        #print(now,newlist[0])
        #print('d', now, newlist[0], newlist[1])
        if newlist[1]>0:
            if now>=0:
                #now*=-1
                print(newlist[0], now)
            else:
                #now*=-1
                print(now,newlist[0])
        else:
            if now>=0:
                print(now, newlist[0])
            else:
                print(newlist[0], now)
            
        now=abs(now)+abs(newlist[0])
        if newlist[1]>0:
            now=now*(-1)
        for xi in range(n-3):
            #print('d', now, newlist[xi+1], newlist[xi+2])
            if newlist[xi+2]>0:
                if now>=0:
                    print(newlist[xi+1], now)
                else:
                    print(now, newlist[xi+1])
                now=-abs(now)-abs(newlist[xi+1])
            else:
                if now>=0:
                    print(now, newlist[xi+1])
                else:
                    print(newlist[xi+1], now)
                now=abs(now)+abs(newlist[xi+1])
        if newlist[-1]>0:
            print(newlist[-1], now)
        else:
            print(now, newlist[-1])
    elif seihu==1:
        newlist=sorted(newlist)
        wa=0
        for nl in range(n):
            wa+=abs(newlist[nl])
        wa-=newlist[0]*2
        print(wa)
        print(newlist[0], newlist[1])
        now=newlist[0]-newlist[1]
        for ll in range(n-2):
            if counter==n-3:
                print(newlist[ll+2], now)
                now=-(abs(now)+abs(newlist[ll+2]))
            else:
                print(now, newlist[ll+2])
                now=-(abs(now)+abs(newlist[ll+2]))
            counter+=1
    elif seihu==-1:
        newlist=sorted(newlist, reverse=True)
        wa=0
        for nl in range(n):
            wa+=abs(newlist[nl])
        wa+=newlist[0]*2
        print(wa)
        print(newlist[0], newlist[1])
        now=newlist[0]-newlist[1]
        for ll in range(n-2):
            if counter==n-3:
                print(now, newlist[ll+2])
                now=(abs(now)+abs(newlist[ll+2]))
            else:
                print(now, newlist[ll+2])
                now=(abs(now)+abs(newlist[ll+2]))
            counter+=1
    
else:
    print(abs(mazu*(len(newlist)-2)))
    for i in range(len(newlist)-2):
        print(mazu*(1-i), mazu)
    if mazu>=0:
        print(mazu, mazu*(3-len(newlist)))
    else:
        print(mazu*(3-len(newlist)), mazu)