Q,Y = map(int, input().split())
S = list(input().split())

def Reverse_Polish_Notation(S, x):
    stack = list()
    N = len(S)
    for i in range(N):
        if S[i] == "+":
            val = 0
            for i in range(2):
                v = stack.pop()
                val += v
            stack.append(val)
        elif S[i] == "min":
            m = stack.pop()
            n = stack.pop()
            val = min(m, n)
            stack.append(val)
        elif S[i] == "max":
            m = stack.pop()
            n = stack.pop()
            val = max(m, n)
            stack.append(val)
        else:
            if S[i]=="X":
                stack.append(x)
            else:
                stack.append(int(S[i]))
    #print(stack)
    return stack[-1]==Y

if Reverse_Polish_Notation(S,0):
    print(0)
    exit()

l = -1
r = 10**13
while r-l>1:
    mid = (r+l)//2
    if Reverse_Polish_Notation(S, mid):
        l = mid
    else:
        r = mid
print(l)