#include<stdio.h>
long long unsigned a[17][17],s,smax;
int n,m,i,j,sol[17];
void solve();
void comut(int lin);
int main()
{
FILE *f=fopen("flip.in","r"), *g=fopen("flip.out","w");
fscanf(f,"%d%d",&n,&m);
for (i=1;i<=n;i++)
    for (j=1;j<=m;++j)
        fscanf(f,"%d",&a[i][j]);
}
int ok(int lin,k)
{
for (int i=1;i<k;++i)
    if (sol[i]>val)
       return 0;
return 0;
}

void solve(int k)
{
for (int lin=0;lin<=n;lin)
    if (ok(lin,k)
       {
       comut(lin);
       solve(++k)
       }
       
if (s>smax)
           smax=s;
}
void comut(int lin)
{
for (j=1;j<=m;++j)
    a[lin][j]=-a[lin][j];
}