A=$<.map{|s|s.split.map &:to_i}
N=A.shift[0]
V=A.pop[0]
B,C=A.transpose
d=[]
N.times{|i|C.sum.downto(C[i]){|j|d[j]=[d[j]||0,B[i]+d[j-C[i]]||=0].max}}
p [1,a=d.index(V)].max
b=d.rindex V
puts a<b ?b: :inf