#include<stdio.h>
int energii[1001],costuri[1001],dp[1001][20001];
int main()
{
	int k,j,i,N,W,min=20000;
	freopen("energii.in","r",stdin);
	freopen("energii.out","w",stdout);
	scanf("%d",&N);
	scanf("%d",&W);
	for(i=1;i<=N;i++)
	{
		scanf("%d",&energii[i]);
		scanf("%d",&costuri[i]);
		if(dp[1][energii[i]]!=0)
		{
			if(dp[1][energii[i]]>=costuri[i])
		     dp[1][energii[i]]=costuri[i];
		}
		else
			dp[1][energii[i]]=costuri[i];
	}
	for(i=2;i<=N;i++)
		for(j=1;j<=10000;j++)
			if(dp[i-1][j]!=0)
			{
				dp[i][j]=dp[i-1][j];
				if(j<=W)
					if(dp[i][j+energii[i]]>(dp[i-1][j]+costuri[i])&&dp[i][j+energii[i]]!=0)
						dp[i][j+energii[i]]=dp[i-1][j]+costuri[i];
					else
						if(dp[i][j+energii[i]]==0)
							dp[i][j+energii[i]]=dp[i-1][j]+costuri[i];
			}
	for(j=W;j<=10000;j++)
		if(dp[N][j]!=0)
			if(dp[N][j]<min)
				min=dp[N][j];
	printf("%d",min);
	return 0;
}