#include <bits/stdc++.h>
using namespace std;

const int INF=1e9;

//map<pair<int,int>,int> dict;

int dict[55][(1<<21)+50];

int mxid=0;
int id[10][10];
int sz[25];
pair<int,int> rec[25];
int w[(1<<21)+50];

int n,W;
int x[55],y[55];
pair<int,int> pi[55];

int sum[55];
vector<pair<int,int>> v[25];
int dp[25][(1<<21)+50];


int mnans=INF;

int dfs(int dep,int mask,int nowans){
//	cerr << "dfs:" << dep << " " << bitset<21>(mask) << endl;
	if (sum[dep-1]-w[mask]>=W){
		mnans=min(mnans,nowans);
		return 0;
	}
	if (dep==n+1) return INF;
//	if (nowans>=mnans) return INF;
//	auto PAIR=make_pair(dep,mask);
	if (dict[dep][mask]!=-1) return dict[dep][mask];
	int ans=INF;
	
	{
		int nowid=id[x[dep]][y[dep]];
		for (auto [m1,s1]:v[nowid]) ans=min(ans,dfs(dep+1,mask^m1,nowans+s1)+s1); 
	}
	
	return dict[dep][mask]=ans;
}

int main(){
//	freopen("B1.in","r",stdin);
	ios_base::sync_with_stdio(false);
	
	mxid=0;
	for (int i=1;i<=6;i++){
		for (int j=i;j<=6;j++){
			id[i][j]=id[j][i]=mxid;
			sz[mxid]=i*j;
			rec[mxid]=make_pair(i,j);
			++mxid;	
		}
	}
	for (int mask=0;mask<(1<<mxid);mask++){
		for (int j=0;j<mxid;j++){
			if ((mask>>j)&1) w[mask]+=sz[j];
		}
	}
	
	for (int i=1;i<=6;i++){
		for (int j=i;j<=6;j++){
		//	cerr << i << " " << j << endl;
			for (int mask=0;mask<(1<<mxid);mask++) dp[id[i][j]][mask]=INF;
			dp[id[i][j]][1<<id[i][j]]=0;
			
			for (int k=1;k<=i-k;k++){
				int id1=id[k][j];
				int id2=id[i-k][j];
				for (auto [m1,s1]:v[id1]){
					for (auto [m2,s2]:v[id2]){
						dp[id[i][j]][m1^m2]=min(dp[id[i][j]][m1^m2],s1+s2+1);
					}
				}
			}
			for (int l=1;l<=j-l;l++){
				int id1=id[i][l];
				int id2=id[i][j-l];
				for (auto [m1,s1]:v[id1]){
					for (auto [m2,s2]:v[id2]){
						dp[id[i][j]][m1^m2]=min(dp[id[i][j]][m1^m2],s1+s2+1);
					}
				}	
			}
			for (int mask=0;mask<(1<<mxid);mask++) if (dp[id[i][j]][mask]!=INF){
			//	if (__builtin_popcount(mask)>6) continue;
				v[id[i][j]].emplace_back(mask,dp[id[i][j]][mask]);	
			}
			
			sort(v[id[i][j]].begin(),v[id[i][j]].end(),
				[&](const pair<int,int> &A,const pair<int,int> &B){
					return A.second<B.second || (A.second==B.second && A.first>B.first);	
				}
			);
			/*
			if (i<=3 && j<=5){
				cerr << i << " " << j << endl;
				cerr << v[id[i][j]].size() << endl;
				for (auto [m1,s1]:v[id[i][j]]){
					cerr << bitset<21>(m1) << "," << s1 << " ";	
				}
				cerr << endl;
			}
			*/
		}
	}
	
	cin >> n >> W;
	W<<=1;
	for (int i=1;i<=n;i++){
		char ch;
		cin >> x[i] >> ch >> y[i];
		pi[i]=make_pair(x[i],y[i]);
	}
	sort(pi+1,pi+n+1);
	for (int i=1;i<=n;i++){
		x[i]=pi[n-i+1].first;
		y[i]=pi[n-i+1].second;
	}
	
	for (int i=1;i<=n;i++) sum[i]=sum[i-1]+x[i]*y[i];
	
	memset(dict,-1,sizeof(dict));
	
	mnans=min(mnans,dfs(1,0,0));
	cout << mnans << "\n";
	return 0;	
}