N=int(input())
ANS=1<<100

for i in range(N):
    S=input()
    while S[0]=="0":
        S=S[1:]

    score=1<<100

    for i in range(2,37):
        try:
            k=int(S,i)
            #print(i,k)
            score=min(score,k)
        except:
            continue
    ANS=min(ANS,score)

print(ANS)