B = gets.to_i
S = gets.chomp
L = S.size
N = S.to_i(B)
#N = gets.to_i(B)
#N = 9**100000

# guchoku
# str = ((0..999).map{|e|e.to_s(B)}*"")
# puts str[0..50]
# puts str[N]

def dig(y, w)
    # range "000".."999"
    i = y/w
    d = y%w
    i.to_s(B)[d] || "0"
end

# deprecated
def climb(x, sz, ofs, w)
    # range "100".."999"
    len = (sz-ofs)*w
    # p [x,sz,ofs,w]
    # p (ofs...sz).map{|e|e.to_s(B)}
    if x >= len
        climb(x-len, sz*B, sz, w+1)
    else
        # p B**(w-1)
        # ((ofs...sz).map{|e|e.to_s(B)}*"")[x]
        dig(x+B**(w-1)*w, w)
    end
end


# deprecated
def climb_flat(x, sz, ofs, w)
    len = (sz-ofs)*w
    while x >= len
        x, sz, ofs, w = x-len, sz*B, sz, w+1
        len = (sz-ofs)*w
    end
    dig(x+B**(w-1)*w, w)
end

# deprecated
def climb_flat2(x)
    ofs, w = 1, 1
    
    len = (B-1)*w # ((B-1)*w)*B**w
    l = 0
    while x >= len
        l += len
        x, ofs, w = x-len, ofs*B, w+1
        len = ofs*(w*(B-1))
    end
    dig(x+len/(B-1), w)
end

# deprecated
def climb_flat3(x)
    
    ((L-10)..(L-1)).each do |w|
        len = ( ((B-1)*(w)+B-1).to_s(B)+"0"*(w)       ).to_i(B)
        sum = ( (w-1).to_s(B)+(B-2).to_s*(w-1)+(B-1).to_s ).to_i(B)
        return dig(x-sum+len/(B-1), w+1) if x < len+sum
    end
    
    len = ( ((B-1)*(L-1)+B-1).to_s(B)+"0"*(L-1)       ).to_i(B)
    sum = ( (L-2).to_s(B)+(B-2).to_s*(L-2)+(B-1).to_s ).to_i(B)
    
    return dig(x-sum+len/(B-1), L)
end


def climb_flat4(x)
    
    ww = len = sum = nil
    L.downto(0) do |w|
        l = ( ((B-1)*(w)+B-1).to_s(B)+"0"*(w)       ).to_i(B)
        s = ( (w-1).to_s(B)+(B-2).to_s*(w-1)+(B-1).to_s ).to_i(B)
        break unless x < l+s
        ww = w
        len = l
        sum = s
    end
    
    return dig(x-sum+len/(B-1), ww+1)
end



if N == 0
    p 0
else
    puts climb_flat2(N-1) if L <= 20
    puts climb_flat4(N-1) unless L <= 20
end