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N = int(input()) ost = [0]*80 ost50 = [0]*80 kpar = 0 for i in range(N): x = int(input()) y = x%80; y1 = (80 - y)%80 if x > 50: kpar += ost[y1] + ost50[y1] ost50[y] += 1 else: kpar += ost50[y1] ost[y] += 1 print(kpar)