# include <stdio.h># include <algorithm># include <string.h>using namespace std;struct node{int w;int v;};struct node a[10010];int n,d,maxa;int vis[10010];int max1(int x,int y){return x>y?x:y;}void dfs(int w1,int w2,int v2,int ans,int flag){if(ans==n){maxa=max1(maxa,v2);return ;}else{for(int i=0;i<n;i++){if(vis[i]==0){vis[i]=1;if(flag&&w1>d+w2){dfs(w1,w2+a[i].w,v2+a[i].v,ans+1,0);}else if(flag&&w1<=d+w2){dfs(w1+a[i].w,w2,v2,ans+1,1);}else if(!flag&&w2>d+w1){dfs(w1+a[i].w,w2,v2,ans+1,1);}else if(!flag&&w2<=d+w1){dfs(w1,w2+a[i].w,v2+a[i].v,ans+1,0);}vis[i]=0;}}}return ;}int main(){while(~scanf("%d%d",&n,&d)){for(int i=0;i<n;i++){scanf("%d%d",&a[i].w,&a[i].v);}memset(vis,0,sizeof(vis));maxa=0;dfs(0,0,0,0,1);printf("%dn",maxa);}return 0;}
