var sum,total,f,map:array[0..1000,0..1000] of longint;
i,j,k,m,n,s,t,ans,r:longint;
begin
readln(m,n);
for i:=1 to m do
for j:=1 to n do read(map[i,j]);
for i:=1 to m do
for j:=1 to n do sum[i,j]:=sum[i,j-1]+map[i,j];
for j:=1 to n do
for i:=1 to m do total[j,i]:=total[j,i-1]+map[i,j];
for i:=1 to m do
for j:=1 to n do
if map[i,j]=1 then
begin
f[i,j]:=1; r:=f[i-1,j-1];
if (sum[i,j-1]-sum[i,j-1-r]=r) and (total[j,i-1]-total[j,i-1-r]=r) then
f[i,j]:=f[i-1,j-1]+1;
if f[i,j]>ans then ans:=f[i,j];
end;
writeln(ans*ans);
end.
var
f:array[0..1000,0..1000] of longint;
i,j,n,m,x,ans:longint;
function min(a,b,c:longint):longint;
begin
if b<a then a:=b;
if c<a then a:=c;
exit(a);
end;
begin
readln(n,m);
ans:=0;
for i:=1 to n do
for j:=1 to m do
begin
read(x);
if x>0 then f[i,j]:=min(f[i-1,j],f[i,j-1],f[i-1,j-1])+1;
if f[i,j]>ans then ans:=f[i,j];
end;
writeln(ans*ans);
end.