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Second solution in Clear category for Pawn Brotherhood by libralibra
def safe_pawns(s):
return sum(bool({chr(ord(x)+k)+str(int(y)-1)for k in(-1,1)}&s)for x,y in s)
if __name__ == '__main__':
#These "asserts" using only for self-checking and not necessary for auto-testing
assert safe_pawns({"b4", "d4", "f4", "c3", "e3", "g5", "d2"}) == 6
assert safe_pawns({"b4", "c4", "d4", "e4", "f4", "g4", "e5"}) == 1
July 6, 2015