def single_number(arr):  
    result = 0  
    for i in arr:  
        result ^= i  
    return result  
  
arr1 = [5, 3, 4, 3, 4]  
arr2 = [3, 2, 5, 2, 1, 5, 3]  
  
print(single_number(arr1))  
print(single_number(arr2)) 