#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 1000000007;
// constexpr int MOD = 998244353;
constexpr int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
constexpr int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    std::cin.tie(nullptr);
    std::ios_base::sync_with_stdio(false);
    std::cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  int n; string s_str, t_str; cin >> n >> s_str >> t_str;
  vector<int> s(n * 2), t(n * 2);
  REP(i, n * 2) {
    s[i] = s_str[i] - '0';
    t[i] = t_str[i] - '0';
  }
  vector<int> ans;
  int match = -1;
  auto op = [&](int x) {
    ans.emplace_back(x);
    FOR(i, x, x + n) s[i] ^= 1;
    if (match != -1) match ^= 1;
  };
  REP(i, n) {
    if ((s[i] | s[i + n]) != (t[i] | t[i + n])) {
      cout << "-1\n";
      return 0;
    }
    if (t[i] == 0 && t[i + n] == 1) {
      if (s[i] == 1) {
        if (s[i + n] == 0) {
          op(n);
          op(i);
        } else {
          op(i);
        }
      }
    } else if (t[i] == 1 && t[i + n] == 0) {
      if (s[i] == 0 && s[i + n] == 1) {
        if (match == -1) {
          op(i);
          match = 0;
        } else if (match == 0) {
          op(n);
          op(i);
        } else {
          op(i);
        }
      } else if (s[i] == 1 && s[i + n] == 0) {
        if (match == -1) {
          match = 1;
        } else if (match == 0) {
          op(i);
        }
      } else if (s[i] == 1 && s[i + n] == 1) {
        if (match == -1) {
          match = 0;
        } else if (match == 1) {
          op(n);
          op(i);
        }
      }
    } else if (t[i] == 1 && t[i + n] == 1) {
      if (s[i] == 0 && s[i + n] == 1) {
        if (match == -1) {
          op(i);
          match = 1;
        } else if (match == 0) {
          op(i);
        } else {
          op(n);
          op(i);
        }
      } else if (s[i] == 1 && s[i + n] == 0) {
        if (match == -1) {
          match = 0;
        } else if (match == 1) {
          op(i);
        }
      } else if (s[i] == 1 && s[i + n] == 1) {
        if (match == -1) {
          match = 1;
        } else if (match == 0) {
          op(n);
          op(i);
        }
      }
    }
  }
  if (match == 0) op(n);
  REP(i, n * 2) assert(s[i] == t[i]);
  assert(ans.size() <= n * 2);
  cout << ans.size() << '\n';
  for (int x : ans) cout << x << '\n';
  return 0;
}