#include <bits/stdc++.h>
using namespace std;
const int N = 500001;
unordered_set<int> hshs[3001];
string s;
int a, b, n;
int dp[5001];
const int MOD = 1e9 + 9;
void add_hashes(int i) {
  long long h = 0;
  for (int j = i; j >= 0; j--) {
    h *= 37;
    h += s[j] - 'a' + 1;
    h %= MOD;
    hshs[i - j + 1].insert(h);
  }
}
int solve(int in) {
  if (in == s.size()) return 0;
  int& res = dp[in];
  if (res != -1) return res;
  res = solve(in + 1) + a;
  string cp = s.substr(0, in);
  if (cp.find(s.substr(in, 1)) == -1) return res;
  int lo = in, hi = n - 1;
  while (lo < hi) {
    int mid = (lo + hi + 1) / 2;
    if (cp.find(s.substr(in, mid - in + 1)) == -1) {
      hi = mid - 1;
    } else {
      lo = mid;
    }
  }
  res = min(res, solve(lo + 1) + b);
  return res;
}
int main() {
  cin >> n >> a >> b >> s;
  memset(dp, -1, sizeof(dp));
  cout << solve(0);
  return 0;
}
