odd and even negatives
\nclass Solution {\npublic:\n    \n    long long maxMatrixSum(vector<vector<int>>& a) {\n        int n = a.size();\n        int m = a[0].size();\n        \n    
```\nclass Solution {\npublic:\n    \n    long long maxMatrixSum(vector<vector<int>>& a) {\n        int n = a.size();\n        int m = a[0].size();\n        \n        int mv = INT_MAX,cnt = 0;\n        long long int sum = 0;\n        bool z = 0;\n \n            for(int i=0;i<n;i++)\n            {\n                for(int j=0;j<m;j++)\n                { \n                    sum += (abs(a[i][j]));\n                    if(a[i][j] == 0)\n                        z = true;\n                    \n                    mv = min(abs(a[i][j]) , mv);\n                    \n                    if(a[i][j]<0)\n                    {\n                        cnt++;                              \n                    }\n                }\n            }\n        return (cnt%2==0?sum:(z?sum:sum-(2*abs(mv))));\n    }\n};\n```
['C']