#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < n; ++i)
typedef long long ll;
using namespace std;

int main() {
    cin.tie(0);
    ios_base::sync_with_stdio(false);

    int N, W, C;
    cin >> N >> W >> C;
    vector<int> v(N), w(N);
    rep(i, N) cin >> w[i] >> v[i];

    vector dp(N + 1, vector<ll>(W + 1));
    rep(i, N) {
        rep(j, W + 1) {
            if (j < w[i])
                dp[i + 1][j] = dp[i][j];
            else {
                dp[i + 1][j] = max(dp[i][j], dp[i + 1][j - w[i]] + v[i]);
                dp[i + 1][j] = max(dp[i + 1][j], dp[i][j - w[i]] + v[i] + C);
            }
        }
    }
    cout << dp[N][W] << "\n";

    return 0;
}