n = int(input())
peaks = []
for _ in range(n):
peaks.append(int(input()))
res = float('inf')
for l in range(100-17+1):
r = l + 17
cost = 0
for p in peaks:
if p < l: cost += (l - p) ** 2
elif p > r: cost += (p - r) ** 2
res = min(res, cost)
print(res)