#include <bits/stdc++.h>
using namespace std;
int a, b, n, i, j;
int f[5001];
int dp[5001][5001];
char s[5003];
int main() {
  while (~scanf("%d%d%d", &n, &a, &b)) {
    scanf("%s", &s[1]);
    for (i = 1; i <= n; i++) f[i] = f[i - 1] + a;
    for (i = 1; i <= n; i++) {
      f[i] = min(f[i], f[i - 1] + a);
      for (j = 1; j < i; j++) {
        if (s[i] == s[j]) {
          dp[i][j] = dp[i - 1][j - 1] + 1;
        } else
          dp[i][j] = 0;
        if (j <= i - dp[i][j]) {
          f[i] = min(f[i], f[i - dp[i][j]] + b);
        } else {
          f[i] = min(f[i], f[j] + b);
        }
      }
    }
    printf("%d\n", f[n]);
  }
}
