GCD and LCM of two numbers in recursive solution

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <string>
#include <cctype>
#include <stack>
#include <queue>
#include <list>
#include <vector>
#include <map>
#include <sstream>
#include <cmath>
#include <bitset>
#include <utility>
#include <set>
#include <numeric>
#include <ctime>

#define Infinity 2147483647
#define Pi acos(-1.0)
#define N 1000000
#define ll long long
#define nodePair pair<int,int>


const int dRow [] = {+1,-1,0,0};
const int dCol [] = {0,+1,+1,-1};

#define loop(i, a) for( int i = (0); i < (a); i++ )
#define loopSize(i, sz) for( size_t i = 0; i < sz.size (); i++ )

#define Set(a, s) memset(a, s, sizeof (a))
#define Max(a, b)  (a < b ? b : a)
#define Min(a, b)  (a > b ? b : a)
using namespace std;

int lcm(int a, int b, int m)
{
    if(a*m % b == 0) return a*m;
    return lcm(a, b, m+1);
}

int gcd(int a, int k)

{
    if(a%k==0)
    {
        return a;
    }
    else
    {
     return gcd(a%k,a);
    }
}

int main()
{
int num1,num2,res;
cin>>num1>>num2;
cout<<"GCD: "<<gcd(num1,num2);
cout<<"LCM: "<<lcm(num1,num2,1);
return 0;
}