#include <bits/stdc++.h>
using namespace std;
int n, a, b, dp[5005];
string s;
vector<int> z_function(string s) {
  int n = (int)s.length();
  vector<int> z(n);
  for (int i = 1, l = 0, r = 0; i < n; ++i) {
    if (i <= r) z[i] = min(r - i + 1, z[i - l]);
    while (i + z[i] < n && s[z[i]] == s[i + z[i]]) ++z[i];
    if (i + z[i] - 1 > r) l = i, r = i + z[i] - 1;
  }
  return z;
}
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> n >> a >> b;
  cin >> s;
  fill(dp, dp + n, 0);
  reverse(s.begin(), s.end());
  dp[n - 1] = a;
  for (int i = n - 2; i >= 0; i--) {
    dp[i] = a + dp[i + 1];
    string ss = s.substr(i);
    vector<int> zf = z_function(ss);
    vector<int> tmx((int)zf.size(), 0);
    int tx = 0;
    for (int j = (int)zf.size() - 1; j >= 0; j--) {
      tx = max(tx, zf[j]);
      tmx[j] = tx;
    }
    for (int j = 0; j < (int)zf.size() - 1; j++)
      if (tmx[j + 1] >= j + 1) dp[i] = min(dp[i], dp[i + j + 1] + b);
  }
  cout << dp[0];
}
