#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, a, b;
  cin >> n >> a >> b;
  string s;
  cin >> s;
  for (int cnt1 = 0; cnt1 <= n / a; ++cnt1) {
    for (int cnt2 = 0; cnt2 <= n / b; ++cnt2)
      if (a * cnt1 + b * cnt2 == n) {
        cout << cnt1 + cnt2 << endl;
        for (int i = 0; i < cnt1; ++i) {
          for (int j = 0; j < a; ++j) cout << s[j];
          cout << endl;
          s.erase(0, a);
        }
        for (int i = 0; i < cnt2; ++i) {
          for (int j = 0; j < b; ++j) cout << s[j];
          cout << endl;
          s.erase(0, b);
        }
        return 0;
      }
  }
  cout << -1 << endl;
  return 0;
}
