def next_bigger(n):
    num_string = list(str(n))
    for i in range(1, len(num_string)):
        if i == len(num_string):
            return -1
 
        #find two the two numbers one bigger than the other with the minimun order
        if num_string[-i] > num_string[-i-1]:
 
            print(num_string[-i])
            print(num_string[-i-1])
 
            aux = num_string[-i]
 
            #interchange the locations:
            num_string[-i] = num_string[-i-1]
            num_string[-i-1] = aux
 
            # create a string from the list
            return int("".join(num_string))
 
print(next_bigger(231))

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