#include <bits/stdc++.h> using namespace std; const long long INF = 1000000000000000000; int main(){ int N, M; cin >> N >> M; vector<vector<long long>> A(N, vector<long long>(M)); for (int i = 0; i < N; i++){ for (int j = 0; j < M; j++){ cin >> A[i][j]; } } vector<long long> S(N, 0); for (int i = 0; i < N; i++){ for (int j = 0; j < M; j++){ S[i] += A[i][j]; } } vector<vector<long long>> dp(N + 1, vector<long long>(2, -INF)); dp[0][0] = 0; for (int i = 0; i < N; i++){ dp[i + 1][0] = max(dp[i][0], dp[i][1] - S[i]); dp[i + 1][1] = max(dp[i][1], dp[i][0] + S[i]); } cout << max(dp[N][0], dp[N][1]) << endl; }