#include <iostream>
#include <fstream>
#include <set>
#include <map>
#include <cstdio>
#include <string>
#include <vector>
#include <algorithm>
#include <random>
#include <chrono>
#include <queue>
#include <unordered_map>
//#include <unordered_set>
#include <iomanip>
#include <stack>
#include <ctime>
#include <cassert>
#include <cmath>
#define y1 ups
#define left lll
#define right rrr
#define next nnn
//#define find fff
typedef unsigned long long ull;
using namespace std;
//mt19937_64 twister(chrono::steady_clock().now().time_since_epoch().count());
//mt19937_64 twister(8888);
//
//long long rnd(long long l, long long r)
//{
// uniform_int_distribution<long long> dis(l, r);
// return dis(twister);
//}
const int mod = (int)1e9 + 9;
//const int mod[2] = {(int)1e9 + 7, (int)1e9 + 9};
//const int st[2] = {887, 8887};'
const int maxn = 1e6 + 88;
const int inf = 1e9 + 88;
const int logn = 22;
const int maxa = 500*500 + 88;
const int block = 775;
const long long infll = 1e18 + 88;
const char sgl[5] = {'a', 'e', 'i', 'o', 'u'};
const int dx[] = {-1, 1, 0, 0};
const int dy[] = {0, 0, -1, 1};
const int knightx[] = {-2, -2, -1, -1, 1, 1, 2, 2};
const int knighty[] = {-1, 1, -2, 2, -2, 2, -1, 1};
const int kingx[] = {-1, -1, -1, 0, 0, 1, 1, 1};
const int kingy[] = {-1, 0, 1, -1, 1, -1, 0, 1};
const char sep = 'a' - 1;
const double eps = 1e-9;
const int maxn1 = 1e3 + 88;
//#define int long long
//
//inline int readint()
//{
// int x = 0;
// char ch = getchar_unlocked();
// while (ch < '0' || ch > '9')
// ch = getchar_unlocked();
// while (ch >= '0' && ch <= '9')
// {
// x = (x << 3) + (x << 1) + ch - '0';
// ch = getchar_unlocked();
// }
// return x;
//}
int a[2588][2588];
string s;
void solve()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
// ifstream cin("input.txt");
// ofstream cout("output.txt");
// ifstream cin("bootfall.in");
// ofstream cout("bootfall.out");
int n, m, i, j, ansv = inf, ansg = inf;
cin >> n >> m;
for (i = 0; i < n; i++)
{
cin >> s;
for (j = 0; j < m; j++)
a[i][j] = s[j] - '0';
}
for (i = 0; i < n; i++)
{
int last = -1;
for (j = 0; j < m; j++)
if (a[i][j] == 0)
{
if (j != last + 1)
ansg = min(ansg, j - last - 1);
last = j;
}
if (last + 1 != m)
ansg = min(ansg, m - last - 1);
}
for (j = 0; j < m; j++)
{
int last = -1;
for (i = 0; i < n; i++)
if (a[i][j] == 0)
{
if (i != last + 1)
ansv = min(ansv, i - last - 1);
last = i;
}
if (last + 1 != n)
ansv = min(ansv, n - last - 1);
}
cout << ansv*ansg;
}
//#undef int
int main()
{
// srand(time(0));
// srand(8);
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
// ifstream cin("input.txt");
// ofstream cout("output.txt");
// ifstream cin("output.txt");
// ifstream fin("12.out");
// int a, b, i = 0;
// while (cin >> a)
// {
// fin >> b;
// if (a != b)
// {
// cout << i << " " << a << " " << b;
// return 0;
// }
// i++;
// }
// freopen("input.txt", "r", stdin);
// freopen("output.txt", "w", stdout);
// freopen("f.in", "r", stdin);
// freopen("f.out", "w", stdout);
// int t = 10000;
// while (t--)
// {
// if (t == 9947)
// t = 9947;
// gen();
// cout << t << endl;
// brut();
// if (!solve())
// {
// cout << "kek";
// return 0;
// }
// }
solve();
return 0;
}
