#include <algorithm>
#include <cstdio>

using namespace std;

const double eps = 1e-6;

struct Candy {
  int v;
  int w;
  bool operator<(const Candy that) const {
    return double(this->v) / this->w - double(that.v) / that.w > eps;
  }
};

int main() {
  int n, w;
  scanf("%d %d", &n, &w);
  Candy c[100];
  for (int i = 0; i < n; i++) {
    scanf("%d %d", &c[i].v, &c[i].w);
  }
  sort(c, c + n);
  int curr_w = 0;
  double curr_v = 0.0;
  for (int i = 0; i < n; i++) {
    if (curr_w + c[i].w <= w) {
      curr_w += c[i].w;
      curr_v += c[i].v;
    } else {
      curr_v += double(w - curr_w) / c[i].w * c[i].v;
      break;
    }
  }
  printf("%.1f\n", curr_v);
  return 0;
}