#include <bits/stdc++.h>

 using namespace std;

 typedef pair<int, int> pii;

 const int maxn = ;

 int equ, var;

 int a[maxn][maxn];

 int x[maxn];

 int free_x[maxn];

 int free_num;

 int ret;

 int gauss() {

     int max_r, col, k;

     free_num = ;

     for(k = , col = ; k < equ && col < var; k++, col++) {

         max_r = k;

         for(int i = k + ; i < equ; i++) {

             if(abs(a[i][col]) > abs(a[max_r][col]))

                 max_r = i;

         }

         if(a[max_r][col] == ) {

             k--;

             free_x[free_num++] = col;

             continue;

         }

         if(max_r != k) {

             for(int j = col; j < var + ; j++)

                 swap(a[k][j], a[max_r][j]);

         }

         for(int i = k + ; i < equ; i++) {

             if(a[i][col] != ) {

                 for(int j = col; j < var + ; j++) {

                     a[i][j] ^= a[k][j];

                 }

             }

         }

     }

     for(int i = k; i < equ; i++) {

         if(a[i][col] != )

             return -;

     }

     if(k < var) return var - k;

     for(int i = var - ; i >= ; i--) {

         x[i] = a[i][var];

         for(int j = i + ; j < var; j++) {

             x[i] ^= (a[i][j] & x[j]);

         }

     }

     return ;

 }

 char G[maxn][maxn];

 int n, m;

 int main() {

     // freopen("in", "r", stdin);

     m = , n = ;

     var = equ = ;

     ret = ;

     memset(a, , sizeof(a));

     for(int i = ; i < n; i++) scanf("%s", G[i]);

     for(int i = ; i < m; i++) {

         for(int j = ; j < n; j++) {

             if(G[i][j] == '') a[i*n+j][var] = ;

             else a[i*n+j][var] = ;

         }

     }

     for(int i = ; i < ; i++) {

         a[i][i] = ;

         if(i %  != ) a[i-][i] = ;

         if(i %  != ) a[i+][i] = ;

         if(i > ) a[i-][i] = ;

         if(i < ) a[i+][i] = ;

     }

     int v = gauss();

     if(v == -) ret = -;

     else if(v != ) {

         ret = maxn;

         int tot =  << v;

         for(int i = ; i < tot; i++) {

             int cnt = ;

             for(int j = ; j < v; j++) {

                 if(i&(<<j)) {

                     x[free_x[j]] = ;

                     cnt++;

                 }

                 else x[free_x[j]] = ;

             }

             for(int j = var - v - ; j >= ; j--) {

                 int idx;

                 for(idx = j; idx < var; idx++) {

                     if(a[j][idx]) break;

                 }

                 x[idx] = a[j][var];

                 for(int l = idx + ; l < var; l++) {

                     if(a[j][l]) x[idx] ^= x[l];

                 }

                 cnt += x[idx];

             }

             ret = min(ret, cnt);

         }

     }

     else for(int i = ; i < var; i++) ret += x[i];

     printf("%d\n", ret);

     vector<pii> va;

     for(int i = ; i < ; i++) {

         if(x[i]) {

             int pos = i + ;

             int r = , c = ;

             while(pos > ) {

                 pos -= ;

                 r++;

             }

             c += pos;

             va.push_back(pii(r, c));

         }

     }

     sort(va.begin(), va.end());

     for(int i = ; i < va.size(); i++) {

         printf("%d %d\n", va[i].first, va[i].second);

     }

     return ;

 }