import math
import csv

with open('data.csv',newline='') as f:
    reader=csv.reader(f)
    file_data=list(reader)

data=file_data[0]
def mean(data):
    n=len(data)
    total=0
    for x in data:
        total +=int(x)

    mean=total/n
    return mean

#squaring and getting the value
squared_list= [] 
for number in data:
    a = int(number) - mean(data) 
    a= a**2 
    squared_list.append(a)

#getting the sum
sum=0
for i in squared_list:
    sum=sum+1

#dividing the sum by total value
result=sum/(len(data)-1)

#finding the square root and the standaed deviation
std_deviation=math.sqrt(result)
print(std_deviation)