#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,n) for (int i = 0; i < n; i++)
#define rrep(i,n) for (int i = n-1; i >= 0; i--)
#define rep2(i,a,b) for (int i = a; i < b; i++)
#define rrep2(i,a,b) for (int i = a-1; i >= b; i--)
#define rep3(i,a,b,c) for (int i = a; i < b; i+=c)
#define rrep3(i,a,b,c) for (int i = a-1; i >= b; i-=c)
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
template<class T> bool chmax(T &a, T b){if (a < b){a = b;return true;} else return false;}
template<class T> bool chmin(T &a, T b){if (a > b){a = b;return true;} else return false;}

int n,v,c;
ll dp[5010][5010];
int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin>>n>>v>>c;
    rep(i,5010)rep(j,5010)dp[i][j]=-1LL<<60;
    dp[0][0]=0;
    rep(i,n){
        int u,w;cin>>u>>w;
        rep(j,v+1){
            chmax(dp[i+1][j],dp[i][j]);
            if((v-j)/u!=0)chmax(dp[i+1][j+((v-j)/u)*u],dp[i][j]+c+w*((v-j)/u));
            if(j+u<=v)chmax(dp[i+1][j+u],dp[i][j]+c+w);
        }
    }
    ll ans=0;
    rep(i,v+1)chmax(ans,dp[n][i]);
    cout<<ans<<"\n";
}