f=open('energii.in')
n=int(f.readline())
ener_min=int(f.readline())
matrice=[[1<<31 for i in range(ener_min+1)]for i in range(n+1)]

i=1
for linie in f:
    linie=linie.split()
    p=int(linie[0])
    g=int(linie[1])
    for j in range(1,ener_min+1):
        if j<=p:
            matrice[i][j]=min(g,matrice[i-1][j])
        else:
            matrice[i][j]=min(matrice[i-1][j],matrice[i-1][j-p]+g)
    i+=1
print(matrice[n][ener_min])

f.close()
f=open('energii.out','w')
f.write(str(matrice[n][ener_min]))
f.close()