#include<cstdio>
#define INF 2000000000
int G, W, e[10002], c[10002], i, j, a[15005], Max, Min=INF;
int main()
{
	freopen("energii.in", "r", stdin);
	freopen("energii.out", "w", stdout);
	
	scanf("%d%d",&G, &W);
	for(i=1;i<=G;i++)
	{
		scanf("%d%d", &e[i], &c[i]);
		if(Max < e[i])
		{
			Max = e[i];
		}
	}
	
	for(i=1;i<=W+Max;i++)
	{
		a[i] = INF;
	}
	
	for(i=1;i<=G;i++)
	{
		for(j=W;j>=0;j--)
		{
			if(a[j] != INF)
			{
				a[j+e[i]] = a[j] + c[i];
			}
		}
	}
	
	for(i=W;i<=W+Max;i++)
	{
		if(Min>a[i])
		{
			Min = a[i];
		}
	}
	printf("%d", Min);
	return 0;
}