B = gets.to_i
D = (S=gets).to_i(B)
n = S.size
n.downto(1){|k|
	if D <= B**k*k-(B**k-1)/(B-1)
		n=k
	end
}
DD = D+(B**n-1)/(B-1)-1
puts (DD/n).to_s(B)[DD%n]