#include <bits/stdc++.h>
using namespace std;
int main() {
  cin.tie(0);
  std::ios::sync_with_stdio(false);
  int x, y, n;
  cin >> n >> x >> y;
  string s;
  cin >> s;
  vector<string> vec;
  int ch = -1, a = 0, b = 0;
  for (int i = 0; i <= n; i++) {
    for (int j = 0; j <= n; j++) {
      if (i * x + j * y == n) ch = i, a = i, b = j;
    }
  }
  if (ch == -1)
    cout << -1 << endl;
  else if (n % y == 0) {
    for (int i = 0; i < n; i += y) vec.push_back(s.substr(i, y));
    cout << vec.size() << endl;
    for (int i = 0; i < vec.size(); i++) cout << vec[i] << endl;
    return 0;
  } else if (n % x == 0) {
    for (int i = 0; i < n; i += x) vec.push_back(s.substr(i, x));
    cout << vec.size() << endl;
    for (int i = 0; i < vec.size(); i++) cout << vec[i] << endl;
    return 0;
  } else if (n % x == y) {
    vec.push_back(s.substr(0, y));
    for (int i = y; i < n; i += x) vec.push_back(s.substr(i, x));
    cout << vec.size() << endl;
    for (int i = 0; i < vec.size(); i++) cout << vec[i] << endl;
    return 0;
  } else if (n % y == x) {
    vec.push_back(s.substr(0, x));
    for (int i = x; i < n; i += y) vec.push_back(s.substr(i, y));
    cout << vec.size() << endl;
    for (int i = 0; i < vec.size(); i++) cout << vec[i] << endl;
    return 0;
  } else {
    int c = 0;
    while (a--) {
      vec.push_back(s.substr(c, x));
      c += x;
    }
    while (b--) vec.push_back(s.substr(c, y)), c += y;
    cout << vec.size() << endl;
    for (int i = 0; i < vec.size(); i++) cout << vec[i] << endl;
  }
  return 0;
}
