def printFrequencies(arr):
dict1 = {}
for i in arr:
if i in dict1:
dict1[i] += 1
else:
dict1[i] = 1
for i,j in dict1.items():
if j == 1:
print(i)
break
arr = [2, 4, 1, 7, 2, 4, 9]
printFrequencies(arr)
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