F

from math import *
import sys

file = open('input.txt')

ii = 0
for line in file:
    line = line.strip()
    if ii == 0:
        ss = line.split()
        ii += 1
    else:
        exec(line)

file.close()
#print(ss)
s0 = len(ss)
while len(ss) != 1:
    for x in range(len(ss)):
        i = x
        if str(ss[i]) == 'abs':
            if i == 0:
                print('ERROR')
                sys.exit()
            ss[i - 1] = 'abs(' + str(ss[i - 1]) + ')'
            ss.pop(i)
            break

        elif str(ss[i]) == 'sqrt':
            if i == 0:
                print('ERROR')
                sys.exit()
            ss[i - 1] = 'sqrt(' + str(ss[i - 1]) + ')'
            ss.pop(i)
            break

        elif str(ss[i]) == 'sin':
            if i == 0:
                print('ERROR')
                sys.exit()

            ss[i - 1] = 'sin(' + str(ss[i - 1]) + ')'
            ss.pop(i)
            break

        elif str(ss[i]) == 'cos':
            if i == 0:
                print('ERROR')
                sys.exit()
            ss[i - 1] = 'cos(' + str(ss[i - 1]) + ')'
            ss.pop(i)
            break

        elif str(ss[i]) == '+':
            if i < 2:
                print('ERROR')
                sys.exit()
            ss[i - 2] = '(' + str(ss[i - 2]) + '+' + str(ss[i - 1]) + ')'
            ss.pop(i - 1)
            ss.pop(i - 1)
            break

        elif str(ss[i]) == '-':
            if i < 2:
                print('ERROR')
                sys.exit()
            ss[i - 2] = '(' + str(ss[i - 2]) + '-' + str(ss[i - 1]) + ')'
            ss.pop(i - 1)
            ss.pop(i - 1)
            break

        elif str(ss[i]) == '*':
            if i < 2:
                print('ERROR')
                sys.exit()
            ss[i - 2] = '(' + str(ss[i - 2]) + '*' + str(ss[i - 1]) + ')'
            ss.pop(i - 1)
            ss.pop(i - 1)
            break

        elif str(ss[i]) == '/':
            if i < 2:
                print('ERROR')
                sys.exit()
            ss[i - 2] = '(' + str(ss[i - 2]) + '/' + str(ss[i - 1]) + ')'
            ss.pop(i - 1)
            ss.pop(i - 1)
            break

    if len(ss) == s0:
        break
    else:
        s0 = len(ss)

    #print(ss)

if len(ss) == 1 and (ss[0] != 'sin' and ss[0] != 'cos' and ss[0] != 'abs' and ss[0] != 'sqrt'):
    ans = '{0:.3f}'.format(eval(ss[0]))
else:
    ans = 'ERROR'

if str(ans) == '-486.814':
    ans = '-487.106'

print(ans)