#include<cstdio>
const long long inf = 1e17+7;
long long f[1005][2];
long long sum[1005];

long long max(long long a,long long b){ return a>b?a:b; }

int main(){
    int n,m;
    scanf("%d%d",&n,&m);
    for(int i = 1; i <= n; i++){
        sum[i] = 0;
        for(int j = 1; j <= m; j++){
            long long u;
            scanf("%lld",&u);
            sum[i] += u;
        }
    }
    f[0][0] = 0;
    f[0][1] = -inf;
    for(int i = 1; i <= n; i++){
        f[i][0] = max(f[i-1][0],f[i-1][1]-sum[i]);
        f[i][1] = max(f[i-1][1],f[i-1][0]+sum[i]);
    }
    printf("%lld\n",max(f[n][0],f[n][1]));
    return 0;
}