#include<bits/stdc++.h>
using namespace std;
const int maxn =3e4+5;
int a[1005][1005]={0},g[maxn][3]={0};
int dp[maxn],pre[maxn],q[maxn];
int n,m,v,w,cnt=-1;
int main(){
	freopen("delicious.in","r",stdin);
	freopen("delicious.out","w",stdout);
	scanf("%d%d",&n,&m);
	for(int i=0;i<n;i++){
		scanf("%d%d",&v,&w);
		if(a[v][w]==0){
			g[++cnt][1]=v;
			g[cnt][2]=w;
		}
		a[v][w]++;
	}
	for(int i=0;i<=cnt;i++){
		memcpy(pre,dp,sizeof(dp));
		for(int j=0;j<g[i][1];j++){
			int head=0,tail=-1;
			for(int k=j;k<=m;k+=g[i][1]){
				if(head<=tail&&k-g[i][1]*a[g[i][1]][g[i][2]]>q[head]){
					head++;
				}
				while(head<=tail&&pre[q[tail]]-(q[tail]-j)/g[i][1]*g[i][2]<=pre[k]-(k-j)/g[i][1]*g[i][2]){
					tail--;
				}
				if(head<=tail){
					dp[k]=max(dp[k],pre[q[head]]+(k-q[head])/g[i][1]*g[i][2]);
				}
				q[++tail]=k;
			}
		}
	}
	printf("%d\n",dp[m]);
	return 0;
}