gistfile1.txt

def answer(str):
    stack = []
    out = ""
    
    for c in str:
        if c == "*":
            stack.append(c)    
        elif c == "+":
            while (peek(stack) == "*"):
                out = out + stack.pop()
            out = out + c
        else:
            out = out + c
            
    while stack:
        out = out + stack.pop()
    
    return out

def peek(stack):
    if stack:
        return stack[-1]
    else:
        return ""