import std.stdio, std.conv, std.string;
import std.array, std.range, std.algorithm, std.container;
import std.math, std.random, std.bigint, std.datetime, std.format;
string read(){ static string[] ss; while(!ss.length) ss = readln.chomp.split; string res = ss[0]; ss.popFront; return res; }

int DEBUG_LEVEL = 0;
void print()(){ writeln(""); }
void print(T, A ...)(T t, lazy A a){ write(t), print(a); }
void print(int level, T, A ...)(T t, lazy A a){ if(level <= DEBUG_LEVEL) print(t, a); }

const long mod = 1_000_000_007;

void main(string[] args){
	if(args.length > 1 && args[1] == "-debug"){
		if(args.length > 2 && args[2].isNumeric) DEBUG_LEVEL = args[2].to!int;
		else DEBUG_LEVEL = 1;
	}
	
	int n = read.to!int;
	long t = read.to!long;
	
	long[] ss, ds;
	foreach(i; 0 .. n){
		ss ~= read.to!long;
		ds ~= read.to!long;
	}
	
	long bestx = 10_000_000, ans = -1;
	foreach(i; 0 .. n){
		long s = ss[i], d = ds[i];
		long x;
		if(s >= t) x = s;
		else x = s + (t - s + d - 1) / d * d;
		
		if(x < bestx){
			bestx = x;
			ans = i + 1;
		}
	}
	
	ans.writeln;


}
