Why does not work? -Basketball Players Project

Question

I thought it should work but why it doesnt? From data science course first project

players = [180, 172, 178, 185, 190, 195, 192, 200, 210, 190]
# ekhtelaf beine har do ta

#mean = average
mean = 0
for i in range(len(players)):
mean += players[i]
mean /= len(players)
print (mean)
# average of sqared differ from the mean

ekhtelaf = list()
x = 0
for i in range(len(players)):
x = mean - players [i]
x = x ** 2
ekhtelaf.append(x)
#sum_ekhtelaf
sum = 0
for adad in ekhtelaf:
sum += adad
#output
var = sum / len(players)
std = var ** (1/2)
print(int(std))