from sys import stdin, exit as sys_exit
f = open('input.txt')
stack = []
dict = {}
a = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'}
s = readline().split()
l = 0
size = 0
for line in f:
    d[line[0]] = line[2:]

for i in s:
    if (s[i] in a):
        stack.append(int(dict[s[i]]))
        size += 1
        l += 1
    else:
        if (size > 0):
            if (s[i] == 'sqrt'):

                p = sqrt(stack[l])
                stack[l] = p


            elif (s[i] == 'sin'):

                p = sin(stack[l])
                stack[l] = p

            elif (s[i] == 'cos'):

                p = cos(stack[l])
                stack[l] = p

            elif (s[i] == abs):

                p = -1 * s[i]
                stack[l] = p
        else:
            print('ERROR')
            sys_exit()


         elif (size > 1):
            if (s[i] == '+'):
                p = s[l] + s[l - 1]
                l -= 1
            elif (s[i] == '-'):
                p = s[l] - s[l - 1]
                l -= 1
            elif (s[i] == '/'):
                p = s[l] / s[l-1]
                stack[l] = p
            elif (s[i] == '*'):
                p = s[l] * s[l-1]
            l -= 1
            size -= 1
            stack[l] = p
         else:
             print('ERROR')
             sys_exit()
if (size == 1):
    print(stack[0])
else:
    print('ERROR')