import java.io.*;
import java.util.*;

public class Main {
    static int[] prices;
    static int[] values;
    static int c;
    static int[][] dp;
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int v = sc.nextInt();
        c = sc.nextInt();
        prices = new int[n];
        values = new int[n];
        for (int i = 0; i < n; i++) {
            prices[i] = sc.nextInt();
            values[i] = sc.nextInt();
        }
        dp = new int[n][v + 1];
        for (int[] arr : dp) {
            Arrays.fill(arr, -1);
        }
        System.out.println(dfw(n - 1, v));
    }
    
    static int dfw(int idx, int p) {
        if (idx < 0) {
            return 0;
        }
        if (dp[idx][p] < 0) {
            dp[idx][p] = dfw(idx - 1, p);
            for (int i = 1; i * prices[idx] <= p; i++) {
                dp[idx][p] = Math.max(dp[idx][p], dfw(idx - 1, p - i * prices[idx]) + c + values[idx] * i);
            }
        }
        return dp[idx][p];
    }
}
    
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}