B = gets.to_i
D = (S=gets).to_i(B)

P=[1]
1.upto(S.size){|i|
	P[i]=P[i-1]*B
}
M=[0]
1.upto(S.size){|i|
	M[i]=i*P[i-1]*(B-1)+M[i-1]
}

n = (1..S.size).bsearch{|k|
	D <= M[k]
}
DD = D+(B**n-1)/(B-1)-1
puts (DD/n).to_s(B)[DD%n]