program task_e;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
 n,m,i,ans,j:longint;
 s1,s2:array[1..200005] of ansistring;
b:boolean;
 s:ansistring;
 c:char;
 f:text;
begin
assign(f,'repair.in');
reset(f);
readln(f,n,m);
for i:=1 to n do
begin
for j:=1 to m do
begin
read(f,c);
s1[j]:=s1[j]+c;
end;
readln(f);
end;

for i:=1 to n do
begin
for j:=1 to m do
begin
read(f,c);
s2[j]:=s2[j]+c;
end;
readln(f);
end;
close(f);
j:=1;
for i:=m+1 to 2*m do
begin
s1[i]:=s1[j];
j:=j+1;
end;


for i:=1 to m do
begin
b:=true;
for j:=1 to m do
begin
if (s2[j]<>s1[j+i-1]) then begin b:=false; break; end;
end;
if (b) then begin ans:=i-1; break;  end;

end;

assign(f,'repair.out');
rewrite(f);
writeln(f,ans);
close(f);

end.