#include <bits/stdc++.h>
using namespace std;
template <class T>
inline T bigMod(T p, T e, T M) {
  T ret = 1;
  for (; e > 0; e >>= 1) {
    if (e & 1) ret = (ret * p) % M;
    p = (p * p) % M;
  }
  return (T)ret;
}
template <class T>
inline T modInverse(T a, T M) {
  return bigMod(a, M - 2, M);
}
template <class T>
inline T gcd(T a, T b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
template <class T>
inline T lcm(T a, T b) {
  a = abs(a);
  b = abs(b);
  return (a / gcd(a, b)) * b;
}
template <class T>
inline string int2String(T a) {
  ostringstream str;
  str << a;
  return str.str();
}
int main() {
  long long n, t;
  scanf("%lld%lld", &n, &t);
  long long s, d;
  pair<long long, long long> mn =
      make_pair(0x3f3f3f3f3f3f3f3f, 0x3f3f3f3f3f3f3f3f);
  for (int i = int(0); i < int(n); i++) {
    scanf("%lld%lld", &s, &d);
    if (s < t) s = s + ((t - s + d - 1) / d) * d;
    mn = min(mn, make_pair(s, (long long)i));
  }
  cout << mn.second + 1 << endl;
  return 0;
}
