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

template< typename T, typename Compare = greater< T > >
vector< T > knapsack_limitations(const vector< int > &w, const vector< int > &m, const vector< T > &v,
                                 const int &W, const T &NG, const Compare &comp = Compare()) {
  const int N = (int) w.size();
  vector< T > dp(W + 1, NG), deqv(W + 1);
  dp[0] = T();
  vector< int > deq(W + 1);
  for(int i = 0; i < N; i++) {
    for(int a = 0; a < w[i]; a++) {
      int s = 0, t = 0;
      for(int j = 0; w[i] * j + a <= W; j++) {
        if(dp[w[i] * j + a] != NG) {
          auto val = dp[w[i] * j + a] - j * v[i];
          while(s < t && comp(val, deqv[t - 1])) --t;
          deq[t] = j;
          deqv[t++] = val;
        }
        if(s < t) {
          dp[j * w[i] + a] = deqv[s] + j * v[i];
          if(deq[s] == j - m[i]) ++s;
        }
      }
    }
  }
  return dp;
}


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

    // w: v*C, v, v, v, ...

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

        v[i] += C;
        m[i] = 1;
    }

    auto a = knapsack_limitations(w, m, v, W, -1);
    cout << *max_element(a.begin(), a.end()) << endl;
}