[백준] 12789번 도키도키 간식드리미 python

n = int(input())
line = list(map(int,input().split()))
passed = []
stack = []
number = 1
while line:
    temp = line.pop(0)
    if temp==number:
        passed.append(temp)
        number+=1
    else:
        stack.insert(0,temp)

    while stack:
        num = stack.pop(0)
        if len(stack)+1>=0 and num==number:
            passed.append(num)
            number+=1
        else:
            stack.insert(0,num)
            break

if not stack:
    print("Nice")
else:
    print("Sad")