a,b=gets.split
x=a.to_i
y=b.to_i
if x<y
  tmp=x
  x=y
  y=tmp
end
if x.between?(1,1000000000)==false then
   puts"Please input [1<= a,b <=1000000000]"
   exit
end

if y.between?(1,1000000000)==false then
   puts"Please input [1<= a,b <=1000000000]"
   exit
end

r=x%y

while r!=0 do
  x=y
  y=r
  r=x%y
end

puts y
