A cryptarithm is an equation where all digits have been replaced with a letter, e.g. AA + BB = CC - this one may have several solutions, with A=1, B=2 and C=3, or A=2, B=3 and C=5, etc.
Your program must read the description of a cryptarithm and output the solution to it.
In this puzzle: - the supplied cryptarithms are all carried out as an addition, - they always have one single solution, - each letter is assigned to a unique digit between 0 and 9 (i.e. two different letters cannot be assigned to the same digit), - the initial letter of a word can never be assigned to 0.
INPUT:
Line 1:N, the number of words to add up. N next lines: a string word containing a word to add up. Next line: a string total containing a word representing the sum of all previous words.
OUTPUT:
X lines: a letter and the digit assigned to it, separated by a space. X is the number of distinct letters in the cryptarithm. The letters must be given in alphabetical order
