n=int(input())
m=2*n+1
x=list(map(int,input().split()))

def f(x):
    one=[(0,1,2),(1,2,0),(2,0,1)]
    two=[(2,1,0),(1,0,2),(0,2,1)]
    while len(x)>1:
        y=[]
        for i in range(len(x)-2):
            tup=(x[i],x[i+1],x[i+2])
            if tup in one:y.append(1)
            elif tup in two:y.append(2)
            else:y.append(0)
        x=y
    return x[0]

if len(x)>200:
    print(0)
else:
    print(f(x))