#!/usr/bin/env python
import sys

# Initialize each variable.
sum = 0.0
sumsq = 0.0
count = 0
mean = 0.0
variant = 0.0

# Read a number from stdin until EOF is found.
line = sys.stdin.readline()
while (line):
  try: 
    number = float(line)
    count += 1
    sum += number
    sumsq += number * number
  except:
    # If an input is not a valid number,
    # read the next input.
    continue
  finally:
    line = sys.stdin.readline()

if count > 0:
  mean = sum / count
  variant = (sumsq / count) - (mean * mean)

print "count: ", count
print "sum: ", sum
print "mean: %5f" % mean
print "variant: %5f" % variant