#include <iostream>
    #include <queue>
    #include <set>
    #include <algorithm>
    #include <random>

    #define mod 1000000007LL
    #define MAX 1'000'000LL
    using namespace std;
    using ll = long long;

    ll n;

    ll dp[2001][101]; // dp[i][j] 일 때, i번째 game에서 hp가 j일 때의 점수
    ll uk;
    pair<ll, ll> games[2001];

    int main(){
        cin >> n >> uk;
        ll result = 0;
        
        for(int i = 1; i <= n; i++) cin >> games[i].first; // score
        for(int i = 1; i <= n; i++){
            cin >> games[i].second; // health
            
            
        }
        for(int i = 0; i <= n; i++){
            for(int j = 0; j < 101; j++){
                dp[i][j] = -1;
            }
        }
        
        
        
        
    //
    //    for(int i = 1; i < n; i++){
    //        for(int j = i+1; j <= n; j++){
    //            for(int k = 1; k < 101; k++){
    //
    //                dp[j][min(k+(uk* (j - i)), 100LL)] = max(dp[i][k], dp[j][min(k+(uk* (j - i)), 100LL)]);
    //                if(!dp[i][k] || k+(uk* (j - i)) - games[j].second < 0) continue;
    //                ll ch = min(100LL, k+(uk* (j - i)) - games[j].second);
    //                dp[j][ch] = max(dp[i][k] + games[j].first, dp[j][ch]);
    //                result= max(dp[j][ch], result);
    //            }
    //        }
    //    }
        dp[0][100] = 0;
        for(int i = 0; i < n; i++){
            for(int j = 0; j <= 100; j++){
                if(dp[i][j] == -1) continue;
                ll ch = min(j+uk, 100LL);
                dp[i+1][ch] = max(dp[i+1][ch], dp[i][j]);
                if(ch - games[i+1].second >= 0){
                    dp[i+1][ch - games[i+1].second] = max(dp[i+1][ch - games[i+1].second], dp[i][j] + games[i+1].first);
                    result = max(result, dp[i+1][ch - games[i+1].second]);
                }
//                cout << dp[i+1][ch] << " " << ch << "  " << i+1 << "\n";
                result = max(result, dp[i+1][min(j+uk, 100LL)]);
            }
        }

        cout << result;
        
        return 0;
    }
    /*
     2 0
     1 2
     99 1
     
     1 5
     1
     100
     */