#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 2500 + 10;
bool a[N][N];
int l[N][N], u[N][N];
int r[N][N], d[N][N];
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
#ifdef LOCAL
freopen("input.txt", "r", stdin);
#endif
int n, m;
cin >> n >> m;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) {
char ch;
cin >> ch;
a[i][j] = ch == '1';
}
}
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) {
if (a[i][j]) {
l[i][j] = l[i][j - 1] + 1;
u[i][j] = u[i - 1][j] + 1;
}
}
}
for (int i = n; i >= 1; i--) {
for (int j = m; j >= 1; j--) {
if (a[i][j]) {
r[i][j] = r[i][j + 1] + 1;
d[i][j] = d[i + 1][j] + 1;
}
}
}
int mx_h = n, mx_w = m;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) {
if (a[i][j]) {
mx_h = min(mx_h, u[i][j] + d[i][j] - 1);
mx_w = min(mx_w, l[i][j] + r[i][j] - 1);
}
}
}
cout << mx_h * mx_w << "\n";
#ifdef LOCAL
cout << "\nTime elapsed: " << double(clock()) / CLOCKS_PER_SEC << " s.\n";
#endif
}
