program Project2;

{$APPTYPE CONSOLE}
var
f:text;
p1,p2, p0:boolean;
s,d:array[1..100000,1..2] of ansistring;
a,b,n,i, n1,n2:longint;
procedure zmin(f,d:longint);
  var k:array[1..1000,1..2] of ansistring;
  i:longint;
  begin
  k[f,d][1]:=s[f,d][b];
  for i:=2 to b do
    k[f,d][i]:=s[f,d][i-1];
    s[f,d]:=k[f,d]
  end;
begin
assign(f, 'repair.in');
reset(f);
readln(f, a, b);
for i:=1 to a do begin
  readln(f, s[i, 1]);
  s[i, 1]:=d[i,1];
  end;
for i:=1 to a do begin
  readln(f, s[i, 2]);
  s[i, 2]:=d[i,2];
  end;
close(f);
n1:=0;
n2:=0;
p0:=true;
for i:=1 to a do
  if s[i,1]<>s[i,2] then p0:=False;
while not p0 do
  begin
  for i:=1 to a do begin
  zmin(i,1);
  zmin(i,2);
  end;
  p1:=true;
  p2:=true;
  for i:= 1 to a do begin
  if d[i,1]<>s[i,2] then p1:=false;
  if d[i,2]<>s[i,1] then p2:=false;
  end;
  if not p1 then inc(n1);
  if not p2 then inc(n2);
  if p1 or p2 then p0:=True;
  end;
assign(f, 'repair.out');
rewrite(f);
if p1 then writeln(f, n1) else if p2 then writeln(f, n2) else
writeln(f, '0');
close(f);
end.