#include <iostream>
#include <map>
#include <vector>
const int64_t A = 37;
const int64_t mod = 1e9 + 7;
const int64_t inf = 1e15;
int main() {
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
int n;
std::string s;
int a, b, c;
std::cin >> n >> s >> a >> b >> c;
std::vector hashes(n, std::vector<int64_t>(n + 1));
std::map<int64_t, std::vector<int>> positions;
for (int i = 0; i < n; ++i) {
int64_t cur_hash = 0;
for (int j = i; j < n; ++j) {
positions[hashes[i][j + 1] = cur_hash = ((cur_hash * A) % mod + s[j]) % mod].push_back(i);
}
}
std::vector dp(n, std::vector<int64_t>(n + 1, inf));
for (int i = 0; i < n; ++i) {
dp[i][i + 1] = a + b;
}
for (int64_t len = 1; len <= n; ++len) {
for (int l = 0; l + len <= n; ++l) {
int r = l + len;
if (l > 0) {
dp[l - 1][r] = std::min(dp[l - 1][r], dp[l][r] + a);
}
if (r < n) {
dp[l][r + 1] = std::min(dp[l][r + 1], dp[l][r] + a);
}
if (c > a * len) {
continue;
}
int64_t hash = hashes[l][r];
auto it = std::lower_bound(positions[hash].begin(), positions[hash].end(), l);
int64_t cnt = 1;
while (it != positions[hash].end() and *it + len <= n) {
dp[l][*it + len] = std::min(dp[l][*it + len], dp[l][r] + cnt * c + (*it + len - l - len * cnt) * a + b);
it = std::lower_bound(positions[hash].begin(), positions[hash].end(), *it + len);
cnt += 1;
}
}
}
std::cout << dp[0][n] - b << '\n';
}
