class name:
    def __init__(this):
        this.KIOKU = {}
    def kiku(this,text):
        this.q = 0
        J = text.split(" ")
        p=0
        for name in J:
            if name == "=>":
                this.KIOKU[J[p+1]] = J[p+2]
            elif name == "=?":
                print(this.KIOKU[J[p+1]])
            elif name == "+":
                this.q = float(J[p+1]) + float(J[p+2])
            elif name == "*":
                this.q = float(J[p+1]) * float(J[p+2])
            elif name == "^":
                this.q = float(J[p+1]) ** float(J[p+2])
            elif name == "/+":
                this.q += float(J[p+1])
            elif name == "/*":
                this.q *= float(J[p+1])
            elif name == "/^":
                this.q = this.q**float(J[p+1])
            elif name == "/=":
                this.KIOKU[J[p+1]] = this.q
            elif name == "=/":
                this.q=this.KIOKU.pop(J[p+1])
            p+=1

    
p=name()
p.kiku("+ 2 2 /= l /^ 0.5 /= k =? k")
p.kiku("=/ l /* 4 /= k =? k")