const N = 60;
let f = [];
for (let i = 0; i < 2 * N; i++) f[i] = new Array(N);
for (let i = 0; i < 2 * N; i++) {
    for (let j = 0; j < N; j++) {
        f[i][j] = new Int32Array(N);
    }
}
let g = [];
g.push('');



let n = 0,
    m = 0;

let buf = '';
process.stdin.on('readable', function () {
    let chunk = process.stdin.read();
    if (chunk) buf += chunk.toString();
});
let getInputNums = line => line.split(' ').filter(s => s !== '').map(x => parseInt(x));
let getInputStr = line => line.split(' ').filter(s => s !== '');
process.stdin.on('end', function () {
    buf.split('\n').forEach(function (line, lineIdx) {
        if (lineIdx === 0) {
            n = getInputNums(line)[0];
            m = getInputNums(line)[1];
        } else if (lineIdx <= n) {
            let arr = getInputNums(line);
            arr.unshift(0);
            g.push(arr);
            if (lineIdx === n) {
                for (let k = 2; k <= m + n; k++) { // k = i1 + j1 
                    for (let i1 = 1; i1 <= n; i1++) {
                        for (let i2 = 1; i2 <= n; i2++) {
                            let j1 = k - i1,
                                j2 = k - i2;
                            if (j1 >= 1 && j1 <= m && j2 >= 1 && j2 <= m) {
                                let t = g[i1][j1];
                                if (i1 !== i2) t += g[i2][j2];   //没有走到同一个点
                                f[k][i1][i2] = Math.max(f[k][i1][i2], f[k - 1][i1 - 1][i2 - 1] + t);
                                f[k][i1][i2] = Math.max(f[k][i1][i2], f[k - 1][i1 - 1][i2] + t);
                                f[k][i1][i2] = Math.max(f[k][i1][i2], f[k - 1][i1][i2 - 1] + t);
                                f[k][i1][i2] = Math.max(f[k][i1][i2], f[k - 1][i1][i2] + t);

                            }
                        }
                    }
                }
                console.log(f[n+m][n][n]);
            }
        }
    });
});