import csv 
with open ('height-weight.csv',newline='') as f :
    reader=csv.reader(f)
    file_data = list(reader)

file_data.pop(0)

new_data=[]
for i in range(len(file_data)) :
    n_num=file_data[i][2]
    new_data.append(float(n_num))

n=len(new_data)
total=0

for x in new_data :
    total+=x
mean=total/n
print(mean)
