def isZeroBinaryString(b):
    for i in b:
        if (i != "0"):
            return False
    return True

def addOne(b):
    if (b == "" or b[0] == "0"):
        return "1" + b[1:]
    else:
        return "0" + addOne(b[1:])

def addBit(a, b):
    if (a == "1"):
        return addOne(b)
    else:
        return b

def addBinary(a, b):
    if (a == ""):
        return b
    if (b == ""):
        return a
    else:
        return addBit(a[0], (addBit(b[0], "0" + addBinary(a[1:], b[1:]))))

def binaryToInt(a):
    n=0
    for i in range(0,len(a),1):
        if a[i] =='1':
            n = n + (2**i)
    return n

def intToBinary(n):
    s=''
    while n > 0:
        if n%2==1:
            n=(n-1)/2
            s= s + '1'
        else:
            n=n/2
            s=s+'0'
    return s


print(addBinary("10", "1"))