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;
#define ll long long
#define int long long
const ll nx=2505, mod=1e9+9;
mt19937 rng(time(0));
ll n, a, b, c, s[nx], dp[nx][nx], pw[nx], mul;
string stmp;
struct update
{
    ll l, r, cnta, cntc;
    update(ll l=0, ll r=0, ll cnta=0, ll cntc=0): l(l), r(r), cnta(cnta), cntc(cntc){}
};
vector<update> calc[nx][nx];
int32_t main()
{
    cin.tie(NULL)->sync_with_stdio(false);
    mul=(rng()%30+30)%30+30;
    cin>>n>>stmp>>a>>b>>c;
    pw[0]=1;
    for (int i=1; i<=n; i++) s[i]=stmp[i-1]-'a'+1, pw[i]=(pw[i-1]*mul)%mod;
    for (int sz=1; sz<=n; sz++)
    {
        map<ll, vector<ll>> mp;
        ll sm=0;
        for (int i=1; i<=sz; i++) sm=(sm+pw[sz-i]*s[i])%mod;
        mp[sm].push_back(1);
        for (int i=sz+1; i<=n; i++) sm=(sm*mul)%mod, sm=((sm-s[i-sz]*pw[sz])%mod+mod)%mod, sm=(sm+s[i])%mod, mp[sm].push_back(i-sz+1);
        for (auto &[_, v]:mp)
        {
            int csz=v.size(), pts=v.size();
            vector<int> pa(csz);
            for (int i=csz-1; i>=0; i--)
            {
                while (pts!=0&&v[i]+sz<=v[pts-1]) pts--;
                if (pts!=v.size()) pa[i]=pts;
                else pa[i]=-1; 
            }
            /*
            cout<<"string update ";
            for (int i=v[0]; i<v[0]+sz; i++) cout<<(char)(s[i]-1+'a');
            cout<<'\n';
            for (int i=0; i<csz; i++) cout<<pa[i]<<' ';
            cout<<'\n';*/
            for (int i=0; i<csz; i++)
            {
                if (pa[i]==-1) continue;
                ll tmp=pa[i], cnt=2;
                while (tmp!=-1) 
                {
                    calc[v[0]][v[0]+sz-1].push_back(update(v[i], v[tmp]+sz-1, v[tmp]+sz-v[i]-cnt*sz, cnt));
                    //cout<<"upd "<<v[i]<<' '<<v[tmp]+sz-1<<' '<<v[tmp]+sz-v[i]-cnt*sz<<' '<<cnt<<'\n';
                    cnt++;
                    tmp=pa[tmp];
                }
            }
        }
    }
    for (int i=1; i<=n; i++) for (int j=1; j<=n; j++) dp[i][j]=1e18;
    for (int i=1; i<=n; i++) dp[i][i]=a;
    for (int sz=0; sz<=n; sz++)
    {
        for (int l=1; l+sz<=n; l++)
        {
            int r=l+sz;
            if (l!=r) dp[l][r]=min({dp[l][r], dp[l+1][r]+a, dp[l][r-1]+a});
            for (auto upd:calc[l][r]) dp[upd.l][upd.r]=min(dp[upd.l][upd.r], dp[l][r]+c*upd.cntc+a*upd.cnta+b);
            //cout<<"dp "<<l<<' '<<r<<' '<<dp[l][r]<<'\n';
        }
    }
    cout<<dp[1][n];
}
Compilation message (stderr)
copypaste3.cpp: In function 'int32_t main()':
copypaste3.cpp:43:24: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   43 |                 if (pts!=v.size()) pa[i]=pts;
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