九度1470

/*


求出每個點向上最多的連續1的個數。
然後看這個1 × x的向左，向右最多可以擴展到哪裏。

*/
#include
#include
using namespace std;

const int maxn = 1000 + 10;
int n , m;
int l[maxn][maxn], r[maxn][maxn], up[maxn][maxn], data[maxn][maxn], dp[maxn][maxn];

void getup(){
   for(int i = 1 ;i <= n; ++i)
        for(int j = 1 ; j<= m; ++ j){
            if(data[i][j]) up[i][j] = up[i-1][j] +1;
            else up[i][j] = 0;
        }
}

void getl(){
    for(int i = 1 ; i<= n;++i){
        for(int j = 1 ;j <= m;++ j){
            int now = j - 1;
            while(up[i][now] >= up[i][j] && now > 0){
                now = l[i][now];
            }
            l[i][j] = now ;
        }
    }
}

void getr()
{
    for(int i = 1 ;i <= n; ++ i)
        r[i][m] = m + 1;
    for(int i = 1 ; i<= n; ++ i)
        for(int j = m ;j >= 1 ; -- j){
            int now = j + 1;
            while(up[i][now] >= up[i][j] && now <= m){
                now = r[i][now];
            }
            r[i][j] = now ;
        }

}

int slove(){
    int ret = 0;
    for(int i = 1 ; i<= n; ++i)
        for(int j = 1 ;j <= m; ++ j){
            ret = max(ret,up[i][j] * (r[i][j] - l[i][j] -1));
        }
    return ret;


}
int main(){
    while(scanf("%d%d",&n,&m) != EOF){
        for(int i = 1 ; i<= n; ++ i)
            for(int j = 1 ;j <= m;++ j)
                scanf("%d",&data[i][j]);
        getup();
        getl();
        getr();
        int ans = slove();
        printf("%d\n",ans);
    }
    return 0;
}