#include <bits/stdc++.h> using namespace std; #define modulo 1000000007 #define mod(mod_x) ((((long long)mod_x+modulo))%modulo) #define Inf 1000000000000000000 int main(){ int N,M; cin>>N>>M; vector<long long> A(N,0); for(int i=0;i<N;i++){ for(int j=0;j<M;j++){ long long t; cin>>t; A[i]+=t; } } 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+1][0],dp[i][1] - A[i]); dp[i+1][1] = max(dp[i+1][1],dp[i][0] + A[i]); dp[i+1][0] = max(dp[i+1][0],dp[i][0]); dp[i+1][1] = max(dp[i+1][1],dp[i][1]); } cout<<max(dp.back()[0],dp.back()[1])<<endl; return 0; }