#include <algorithm>
#include <cstdio>

const int MAX_G = 15000;

int dp[2 + MAX_G];

struct Energy {
  int g;
  int val;
};

int main() {
  freopen("energii.in", "r", stdin);
  freopen("energii.out", "w", stdout);
  int g, n;
  scanf("%d%d", &n, &g);
  Energy energy[2 + n];
  for (int i = 1; i <= n; i++)
    scanf("%d%d", &energy[i].g, &energy[i].val);
  for (int sum = 1; sum <= MAX_G; sum++)
    dp[sum] = 2e9;
  dp[0] = 0;
  for (int i = 1; i <= n; i++)
    for (int sum = g - 1; sum >= 0; sum--) {
      int j = std::min(sum + energy[i].g, g);
      dp[j] = std::min(dp[j], dp[sum] + energy[i].val);
    }
  if (dp[g] == 2e9)
    printf("-1");
  else
    printf("%d", dp[g]);
  return 0;
}