This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std;
    
typedef long long ll;
const int  N = 2500 + 2,MOD = (int)1e9 + 7;
struct H{
    int p,mod;
    vector<ll> h,inv;
    ll binpow(ll a,ll b) {
        ll ret = 1,k = a;
        while(b) {
            if(b & 1) {
                ret *= k;
                ret %= mod;
            }
            k *= k;
            k%=mod;
            b /= 2;
        }
        return ret;
    }
    void init(string s) {
        int n = (int)s.size();
        h.resize((int)s.size());
        inv.resize((int)s.size());
        ll x = 1;
        for(int i = 0;i < n;i++) {
            h[i] = x * 1ll * (s[i] - 'a' + 1)%mod;
            if(i) h[i] += h[i - 1];
            if(h[i] >= mod) h[i] -= mod;
            inv[i] = binpow(x,mod-2);
            x = x * 1ll * p%mod;
        }
    }
    int get(int l,int r) {
        ll val = h[r];
        if(l) {
            val -= h[l - 1];
        }
        if(val < 0) val += mod;
        val = val * inv[l]%mod;
        return val;
    }
}xx,yy;
string s;
ll a,b,c;
int n;
ll dp[N][N];
int nx[N][N];
vector<pair<pair<int,int>,pair<int,int>>> f;
vector<array<int,3>> x;
void test() {
    cin >> n >> s >> a >> b >> c;
    yy.p = 37;yy.mod = 998244353;yy.init(s);
    xx.p = 167;xx.mod = (int)1e9 + 7;xx.init(s);
    bool sub = true;
    for(int i = 0;i < n;i++) {
        if(s[i] != 'a') {
            sub = false;
        }
    }
    ll res = n * 1ll * a;
    for(int i = 0;i < n;i++) {
        for(int j = i;j < n;j++) {
            int ff = xx.get(i,j),tt = yy.get(i,j);
            f.push_back({{ff,tt},{i,j}});
        }
    }
    sort(f.begin(),f.end());
    for(int i = 0;i < (int)f.size();) {
        vector<pair<int,int>> k;
        int e = i;
        while(e < (int)f.size() && f[e].first == f[i].first) {
            k.push_back(f[e].second);
            e++;
        }
        i = e;
        int it = (int)k.size() - 1;
        for(int j = (int)k.size() - 1;j >= 0;j--) {
            while(it >= 0 && k[it].first > k[j].second) {
                it--;
            }
            if(it == (int)k.size() - 1) {
                nx[k[j].first][k[j].second] = -1; 
            } else {
                nx[k[j].first][k[j].second] = k[it + 1].first;
            }
        }
    }
    for(int l = 0;l < n;l++) {
        for(int r = 0;r < n;r++) {
            dp[l][r] = 1e18;
        }
    }
    for(int i = 0;i < n;i++) {
        dp[i][i] = a;
    }
    for(int s = 1;s <= n;s++) {
        for(int l = 0;l + s - 1 < n;l++) {
            x.push_back({s,l,l + s - 1});
        }
    }
    for(auto [s,l,r]:x) {
        dp[l][r] = min({dp[l][r],dp[l + 1][r] + a,dp[l][r - 1] + a});
        int l_ = l,r_ = r;
        int occ = 1;
        int len = (r - l + 1);
        // cout << l << ' ' << r << ' ' << dp[l][r] << '\n';
        while(l_ != -1) {
            // cout << l_ << "x\n";
            int sz = (r_ - l + 1);
            ll val = (sz - occ * 1ll * len) * 1ll * a + b + occ * c + dp[l][r];
            dp[l][r_] = min(dp[l][r_],val);
            occ++;
            l_ = nx[l_][r_];
            r_ = l_ + len - 1;
        }
    }
    cout << dp[0][n-1] << '\n';
}
signed main() {
    ios_base::sync_with_stdio(false);cin.tie(0);
    int t = 1; 
    // cin >> t;
    while(t--) {
        test();
    }
}  
Compilation message (stderr)
copypaste3.cpp: In function 'void test()':
copypaste3.cpp:58:10: warning: variable 'sub' set but not used [-Wunused-but-set-variable]
   58 |     bool sub = true;
      |          ^~~
copypaste3.cpp:64:8: warning: unused variable 'res' [-Wunused-variable]
   64 |     ll res = n * 1ll * a;
      |        ^~~| # | Verdict  | Execution time | Memory | Grader output | 
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