先看题目：https://ac.nowcoder.com/acm/problem/16710
解题思路：
公式lcm(a,b) = ab / gcd(a,b)
记得要先a/gcd(a,b)然后再乘b以防止越界
*代码：**

#include<bits/stdc++.h>
using namespace std;
typedef unsigned long long ull;
ull gcd(ull a, ull b)
{
    return b == 0 ? a : gcd(b, a%b);
}
int main()
{
    ull a, b;
    cin >> a >> b;
    ull m = gcd(a, b);
    cout << a/m * b << endl;
}