#!/usr/bin/env python

import sys

loadfile = sys.stdin

if len(sys.argv) == 1:
	print "No command to run"
	sys.exit(1)

if len(sys.argv) == 3:
	if sys.argv[2] != "-":
		loadfile = open(sys.argv[2])

def add(x, y):
	return x + y

def sub(x, y):
	return x - y

def mult(x, y):
	return x * y

def div(x,y):
	return x / y;

lis = []
for line in loadfile:
	if line.strip() <> "":
		x = float(line)
		lis.append(x)

print reduce(eval(sys.argv[1]), lis)