Pair sort

count = int(input())
nums = [int(aa)-1 for aa in input().strip().split(" ")]

numsPosDict = [[-1,-1] for _ in range(count)]

for ii in range(count*2):
    # print(nums[ii], ii)
    if numsPosDict[nums[ii]][0] == -1:
        numsPosDict[nums[ii]][0] = ii
    else:
        numsPosDict[nums[ii]][1] = ii

swaps = [[-1,-1] for _ in range(count-1)]
for ii in range(count-1):
    # print(ii,numsPosDict[nums[ii*2]])
    swaps[ii][0] = ii*2+1
    swaps[ii][1] = numsPosDict[nums[ii*2]][1]
    tmp = nums[numsPosDict[nums[ii*2]][1]]
    nums[numsPosDict[nums[ii*2]][1]] = nums[ii*2+1]
    nums[ii*2+1] = tmp
print(len(swaps))
for aa, bb in swaps:
    print(aa+1,bb+1)

# print(numsPosDict)

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: WRONG ANSWER