#include <bits/stdc++.h>

using namespace std;
const int NMAX = 1010;

int width, height;
int area, maxarea;
int N, M;
int H[NMAX][NMAX], W[NMAX][NMAX], m[NMAX][NMAX];

int afisare_matrice(int mat[NMAX][NMAX]){
    for(int i = 1; i <= N; i++){
        for(int j = 1; j <= M; j++){
            printf("%d", mat[i][j]);
            if(mat[i][j] >= 10)
                printf(" ");
            else
                printf("  ");
        }
        printf("\n");
    }
}

int OK(int i, int j){
    if(i < 1 || j < 1 || i > N || j > M)
        return false;
    return true;
}

int main(){

    freopen("fadema.in", "r", stdin);
    freopen("fadema.out", "w", stdout);

    scanf("%d%d", &N, &M);

    for(int i = 1; i <= N; i++)
        for(int j = 1; j <= M; j++)
            scanf("%d", &m[i][j]);

    for(int i = 1; i <= N; i++){
        for(int j = 1; j < M; j++){
            if(j == 1)
                W[i][j] = 1;

            if(m[i][j + 1] != m[i][j])
                W[i][j + 1] = W[i][j] + 1;
            else
                W[i][j + 1] = 1;
        }
    }

    for(int i = 1; i < N; i++){
        for(int j = 1; j <= M; j++){
            if(i == 1)
                H[i][j] = 1;

            if(m[i + 1][j] != m[i][j])
                H[i + 1][j] = H[i][j] + 1;
            else
                H[i + 1][j] = 1;
        }
    }

    maxarea = 1;

    afisare_matrice(W);
    printf("%\n\n");
    afisare_matrice(H);
    printf("%\n\n");

    for(int i = 1; i <= N; i++){
        for(int j = 1; j <= M; j++){
            //height = H[i][j];
            width = 1e7;
            for(int k = i - H[i][j] + 1; k <= i; k++){
                width = min(width, W[k][j]);
                area = H[k][j] * width;
                maxarea = max(maxarea, area);
            }
            //cout << height << ' ' << width << "  -  (" << i << ", " << j << ")\n";
        }
    }

    printf("%d", maxarea);

    return 0;
}