print "Zadaj K: "; $K = readline.to_i
print "Zadaj M: "; $M = readline.to_i

citacie = Array.new($K, 0)

$M.times {
  print "Zadaj i,j: "; r = readline.split(","); i=r[0].to_i-1; j=r[1].to_i-1
  citacie[j] += 1 if j < $K and i >= $K
}

# pouzijem qsort v standardnej kniznici, popis algoritmu vid minule vzoraky
citacie = citacie.sort.reverse

p citacie

hindex = $K > citacie[0] ? $K : citacie[0]
hindex -= 1 while hindex > 0 and citacie[hindex-1] < hindex

puts hindex