20250627

"""n=int(input())a=[]a=list(input().split())for i in range(n-1, -1, -1) :    print(a[i], end=' ')""""""n=int(input())if n==0 :    print(0)else :    while(n) :        print(n%10, end='')        n=n//10"""n=int(input())a=[]s=0for i in range(n) :    b=0    b=int(input())    if a==0 :        a.pop()    else :        a.append(a)for i in range(len(a)) :    s+=a.pop()