def big_data_add(a,b):
    max_len=len(a) if len(a)>len(b) else len(b)
    a=a.zfill(max_len)
    b=b.zfill(max_len)
    a=list(a)
    b=list(b)
    result=[0]*(max_len+1)
    for i in range(max_len-1,-1,-1):
        temp=int(a[i])+int(b[i])
        temp+=result[i+1]
        if temp>=10:
            result[i+1]=temp%10
            result[i]=temp//10
        else:
            result[i+1]=temp
    return result
result=big_data_add('123456','456123')
c=''
for i in range(len(result)):
    c+=str(result[i])
print(c.lstrip('0'))