#include <bits/stdc++.h>
using namespace std;
const int N = 5e3 + 5;
int n, a, b, dp[N], z[N];
string s;
void get_z(string ns) {
  int l = 0, r = 0;
  int len = ns.length();
  for (int i = 1; i < len; i++) {
    if (i > r) {
      l = r = i;
      while (r < len && ns[r - l] == ns[r]) r++;
      z[i] = r - l, r--;
    } else {
      int k = i - l;
      if (z[k] < r - i + 1)
        z[i] = z[k];
      else {
        l = i;
        while (r < len && ns[r - l] == ns[r]) r++;
        z[i] = r - l, r--;
      }
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cin >> n >> a >> b;
  cin >> s;
  dp[0] = a;
  for (int i = 1; i < n; i++) {
    dp[i] = dp[i - 1] + a;
    string ns = s.substr(0, i + 1);
    reverse(ns.begin(), ns.end());
    get_z(ns);
    for (int j = 1; j <= i; j++)
      if (z[j]) {
        if (z[j] <= j)
          dp[i] = min(dp[i], dp[i - z[j]] + b);
        else
          dp[i] = min(dp[i], dp[i - j] + b);
      }
  }
  cout << dp[n - 1] << endl;
  return 0;
}
