#include <bits/stdc++.h>
using namespace std;
const long long N = 3e5 + 5;
const long long mod = 1e9 + 7;
const long long inf = 1e18;
const long long X = 1e7;
int dx[] = {0, 0, -1, 1};
int dy[] = {1, -1, 0, 0};
pair<int, int> vis[100][100][100];
char ch[100][100];
deque<pair<pair<int, int>, int>> dq;
void vert(pair<pair<int, int>, int> dl, int &a, int &b, int &c) {
  a = dl.first.first;
  b = dl.first.second;
  c = dl.second;
}
void flag(int a, int b, int c, int x, int y) {
  vis[a][b][c] = {x, y};
  vis[a][c][b] = {x, y};
  vis[b][a][c] = {x, y};
  vis[b][c][a] = {x, y};
  vis[c][a][b] = {x, y};
  vis[c][b][a] = {x, y};
}
void do_it(int a, int b, int c, int x) {
  if (x == a || x == b || x == c) return;
  if (!vis[a][b][x].first && ch[a][b] == ch[c][x]) {
    flag(a, b, x, c, x);
    dq.push_back({{a, b}, x});
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  cerr.tie(nullptr);
  int n;
  cin >> n;
  int x, y, z;
  cin >> x >> y >> z;
  for (long long i = 1; i <= n; i++)
    for (long long j = 1; j <= n; j++) cin >> ch[i][j];
  dq.push_front({{x, y}, z});
  flag(x, y, z, -1, -1);
  while (dq.size()) {
    int a, b, c;
    vert(dq.front(), a, b, c);
    dq.pop_front();
    for (long long i = 1; i <= n; i++) do_it(b, c, a, i);
    for (long long i = 1; i <= n; i++) do_it(a, b, c, i);
    for (long long i = 1; i <= n; i++) do_it(c, a, b, i);
  }
  if (vis[1][2][3].first == 0) {
    cout << -1;
    return 0;
  }
  vector<pair<int, int>> ans;
  int a = 1, b = 2, c = 3;
  while (vis[a][b][c].first != -1) {
    int u = vis[a][b][c].first;
    int v = vis[a][b][c].second;
    ans.push_back({u, v});
    if (a == v) a = u;
    if (b == v) b = u;
    if (c == v) c = u;
  }
  reverse(ans.begin(), ans.end());
  cout << ans.size() << "\n";
  for (auto x : ans) cout << x.first << " " << x.second << "\n";
}
