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


ifstream in("energii.in");
ofstream out("energii.out");
int elemente,profit[1001],cost[1001];
int capacitate;

void read()
{
    in>>elemente>>capacitate;
    for(int i=0; i<elemente; i++)
    {
        in>>profit[i]>>cost[i];
    }
}

int dp[1002][5002];


int knapsack(int index,int cap)
{

    if(index==-1 && cap>0)
    {
        return 99999999;
    }
    if(cap<=0)
    {
        return 0;
    }
    else
    {
        int a=knapsack(index-1,cap);
        int b=cost[index]+knapsack(index-1,cap-profit[index]);
        return min(a,b);
    }


}


int main()
{
    read();
    out<<knapsack(elemente-1,capacitate);


}