rt,本来以为是long long，结果发现开了unsigned long long都不行。。。。。。

#include <bits/stdc++.h>
using namespace std;
#define int unsigned long long
const int N = 1e6 + 5;
int Left, Right;
int AnswerSize = 0;
int AnswerLeft[N], AnswerRight[N];
signed main () {
	cin >> Left >> Right;
	while (Left != Right) {
		int i = 0;
		while (Left % (1 << (i + 1)) == 0 && Left + (1 << (i + 1)) <= Right) {
			++i;
		}
		AnswerLeft[++AnswerSize] = Left;
		AnswerRight[AnswerSize] = Left + (1 << i);
		Left += (1 << i);
	}
	cout << AnswerSize << endl;
	for (int i = 1; i <= AnswerSize; ++i) {
		cout << AnswerLeft[i] << ' ' << AnswerRight[i] << endl;
	}
	return 0;
}

第三个样例会TLE