Ruudukko

const rl = require('readline').createInterface({
  input: process.stdin,
  output: process.stdout,
  terminal: false
});

let n; 
let arr;
let c = 0;

rl.on('line', line => {
  if (!n) {
    n = Number(line);
    arr = new Array(n);
    return;
  }

  arr[c] = line.split('');
  if (++c === n) rl.close();
});

rl.on('close', () => {
  arr[0][0] = '.';
  arr[n-1][n-1] = '.';
  let sumArr = new Array(n);
  for (let i = 0; i < n; i++) sumArr[i] = new Array(n).fill(0);

  let yc = 0;
  for (let i = 0; i < n; i++) {
    if (arr[0][i] === 'o') yc++;
    sumArr[0][i] = yc;
  }

  let vrc = 0;
  for (let i = 0; i < n; i++) {
    if (arr[i][0] === 'o') vrc++;
    sumArr[i][0] = vrc;
  }

  for (let i = 1; i < n; i++) {
    for (let j = 1; j < n; j++) {
      sumArr[i][j] = Math.max(sumArr[i-1][j], sumArr[i][j-1]);
      if (arr[i][j] === 'o') sumArr[i][j]++;
    }
  }

  console.log(sumArr[n-1][n-1]+1);
});

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3

Verdict: ACCEPTED

Test 3

Group: 1, 2, 3

Verdict: ACCEPTED

Test 4

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 5

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 6

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 7

Group: 2, 3

Verdict: ACCEPTED

Test 8

Group: 2, 3

Verdict: ACCEPTED

Test 9

Group: 2, 3

Verdict: WRONG ANSWER

Test 10

Group: 2, 3

Verdict: WRONG ANSWER

Test 11

Group: 2, 3

Verdict: WRONG ANSWER

Test 12

Group: 2, 3

Verdict: WRONG ANSWER

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: WRONG ANSWER

Test 16

Group: 3

Verdict: WRONG ANSWER

Test 17

Group: 3

Verdict: WRONG ANSWER

Test 18

Group: 3

Verdict: WRONG ANSWER