#include <bits/stdc++.h>
inline int read() {
  int x = 0;
  bool f = 1;
  char ch = getchar();
  while (!isdigit(ch))
    if (ch == '-') f = 0;
  while (isdigit(ch)) {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return (f) ? x : -x;
}
inline void write(int x) {
  if (x < 0) putchar('-'), x = -x;
  if (x > 9) write(x / 10);
  putchar(x % 10 + 48);
}
int a[100001], b[100001];
int main() {
  int n = read(), h = read(), xn = n, xh = h, s = 0, maxv = -1;
  for (int i = 1; i <= n; ++i) {
    a[i] = read(), b[i] = read();
    if (a[i] > maxv) maxv = a[i];
  }
  do {
    --n;
    ++s;
    h -= b[n];
  } while (h > 0 || n == 0);
  if (h <= 0) {
    write(s);
    putchar('\n');
    return 0;
  }
  s += (h - 1) / maxv + 1;
  write(s);
  putchar('\n');
  return 0;
}
