#include <algorithm>
#include <stdio.h>

const int MAX_G = 15000;

int dp[1 + MAX_G];

struct Object {
  int p;
  int g;
};

int main() {

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

  int n, g;
  scanf("%d%d", &n, &g);
  Object objects[1 + n];
  for (int i = 1; i <= n; i++)
	scanf("%d%d", &objects[i].g, &objects[i].p);
  for (int j = 1; j <= MAX_G; j++)
	dp[j] = 2e9;
  for (int i = 0; i <= g; i++)
    for (int j = 1; j <= n; j++) {
	  int price = std::min(i + objects[j].g, g);
	  if (dp[i] + objects[j].p < dp[price])
		dp[price] = dp[i] + objects[j].p;
    }

  if (dp[g] == 2e9)
    dp[g] = -1;
  printf("%d\n", dp[g]);

  fclose(stdin);
  fclose(stdout);

  return 0;
}