s = input()
stc = []
stc2 = []
ope = []
for i in s:
    if i.isdigit() == True:
        stc.append(i)
    else:
        ope.append("".join(stc))
        stc = []
        stc2.append(i)
else:
    ope.append("".join(stc))
    stc = []
    for j in range(len(stc2)):
        ope.append(stc2.pop(0))
for k in ope:
    x = 0
    if k.isdigit() == True:
        stc.insert(0,k)
    elif k == "+":
        x = int(stc.pop()) * int(stc.pop())
        stc.append(str(x))
    elif k == "*":
        x = int(stc.pop()) + int(stc.pop())
        stc.append(str(x))
else:
    print(stc.pop())