Educational Codeforces Round 92 (Rated for Div. 2) A. LCM Problem（构造）

A. LCM Problem
time limit per test2 seconds
memory limit per test256 megabytes
inputstandard input
outputstandard output
Let LCM(x,y) be the minimum positive integer that is divisible by both x and y. For example, LCM(13,37)=481, LCM(9,6)=18.

You are given two integers l and r. Find two integers x and y such that l≤x

Input
The first line contains one integer t (1≤t≤10000) — the number of test cases.

Each test case is represented by one line containing two integers l and r (1≤l

Output
For each test case, print two integers:

if it is impossible to find integers x and y meeting the constraints in the statement, print two integers equal to −1;
otherwise, print the values of x and y (if there are multiple valid answers, you may print any of them).
Example
inputCopy
4
1 1337
13 69
2 4
88 89
outputCopy
6 7
14 21
2 4
-1 -1

题意：
给定范围lr
让你在范围内找到xy使得lcm（x，y）也在范围内
思路：
构造 贪心
找最小的x和2x
令y=2x，
lcm必然等于y
如果都在范围内，直接输出

int main() {
    int T;
    read(T);
    while(T--) {
        int l,r;
        read(l);
        read(r);
        if(l*2>r)puts("-1 -1");
        else cout<<l<<" "<<l*2<<endl;
    }
    return 0;
}