A positive integer is called an Armstrong number of order n if

abcd... = a^{n} + b^{n} + c^{n} + d^{n} + ...

In case of an Armstrong number of 3 digits, the sum of cubes of each digits is equal to the number itself. For example:

153 = 1*1*1 + 5*5*5 + 3*3*3 // 153 is an Armstrong number.