HDU 1796 容斥原理 How many integers can you find

#include  
#include  
using namespace std;  
#define LL long long  
#define N 11  
  
LL num[N],ans,n;  
int m,cnt;  
  
LL gcd(LL a,LL b)  
{  
    int t;  
    while(b)  
    {  
        t=a%b;  
        a=b;  
        b=t;  
    }  
    return a;  
}  
  
  
void dfs(int id,bool flag,LL LCM)  
{  
    LCM=num[id]/gcd(num[id],LCM)*LCM;  
    if(flag)ans+=n/LCM;  
    else ans-=n/LCM;  
    int i;  
    for(i=id+1;i