#include <bits/stdc++.h>
using namespace std;
signed main() {
  int n, a, b;
  cin >> n >> a >> b;
  string s;
  cin >> s;
  vector<int> dp(n + 1, INT_MAX);
  vector<vector<int> > lcp(n, vector<int>(n));
  for (int i = n - 1; i >= 0; --i) {
    for (int j = n - 1; j >= 0; --j) {
      if (s[i] == s[j]) {
        if (i == n - 1 || j == n - 1) {
          lcp[i][j] = 1;
        } else {
          lcp[i][j] = 1 + lcp[i + 1][j + 1];
        }
      }
    }
  }
  dp[0] = 0;
  for (int i = 0; i < n; ++i) {
    dp[i + 1] = min(dp[i + 1], dp[i] + a);
    for (int j = 0; j < i; ++j) {
      int k = min(lcp[i][j], i - j);
      dp[i + k] = min(dp[i + k], dp[i] + b);
    }
  }
  cout << dp[n];
}
