#include <cstdio>
#include <algorithm>
#define MAXIM 10002

using namespace std;

int dp[1005][10005], g, w, e, c;

void umple()
{
    for(int i=0; i<=w; i++)
        dp[0][i]=MAXIM;
}


int main()
{

    freopen("energii.in", "r", stdin);
    freopen("energii.out", "w", stdout);

    scanf("%d %d", &g, &w);
    umple();

    for(int i=1; i<=g; i++)
    {
        scanf("%d %d", &e, &c);
        for(int j=0; j<=e; j++)
            dp[i][j]=min(dp[i-1][j], c);
        for(int j=e+1; j<=w; j++)
            dp[i][j]=min(dp[i-1][j], dp[i-1][j-e]+c);

    }
    printf("%d", dp[g][w]);

    return 0;
}