Untitled diff
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#include<bits/stdc++.h>
#include<bits/stdc++.h>
using namespace std;
using namespace std;
//#define debug(...)   printf( __VA_ARGS__ )
//#define debug(...)   printf( __VA_ARGS__ )
#define debug(...)   /****nothing****/
#define debug(...)   /****nothing****/
#define ll long long
#define ll long long
#define ull unsigned long long
#define ull unsigned long long
#define pb push_back
#define pb push_back
#define mem(arr,val)    memset(arr,val,sizeof(arr))
#define mem(arr,val)    memset(arr,val,sizeof(arr))
#define mp make_pair
#define mp make_pair
#define pii pair<int,int>
#define pii pair<int,int>
#define F first
#define F first
#define S second
#define S second
#define sz(x) (int)(x).size()
#define sz(x) (int)(x).size()
#define nopos string::npos
#define nopos string::npos
#define fr(i,a,b) for(i=a;i<=b;i++)
#define fr(i,a,b) for(i=a;i<=b;i++)
#define frn(i,a,b) for(i=a;i>=b;i--)
#define frn(i,a,b) for(i=a;i>=b;i--)
set<int> st;
set<int> st;
int n,m,i,j,k;
int n,m,i,j,k;
int main()
int main()
{
{
    //freopen("d://i.txt","r",stdin);
    //freopen("d://i.txt","r",stdin);
    //freopen("d://o.txt","w",stdout);
    //freopen("d://o.txt","w",stdout);
    cin>>n>>m;
    cin>>n>>m;
    int fl2=1; // every group is not full of traitor
    int fl2=1; // every group is not full of traitor
    int cnt=0;
    int cnt=0;
    while(m--)
    while(m--)
    {
    {
        scanf("%d",&k);
        scanf("%d",&k);
        int fl=0; // assume all are traitor in this group
        int fl=0; // assume all are traitor in this group
        while(k--)
        while(k--)
        {
        {
            scanf("%d",&j);
            scanf("%d",&j);
            auto it=st.lower_bound(-j);
            auto it=st.lower_bound(-j);
            if(it!=st.end() && *it==-j)
            if(it!=st.end() && *it==-j)
            {
            {
                fl=1;
                fl=1;
                break;
            }
            }
            st.insert(j);
            st.insert(j);
        }
        }
        if(fl==0) // all are traitor in this group
        if(fl==0) // all are traitor in this group
        {
        {
            fl2=0; // at least one group is all are traitor
            fl2=0; // at least one group is all are traitor
            break;
            break;
        }
        }
        st.clear();
        st.clear();
    }
    }
    printf((fl2==0)?"YES":"NO");
    printf((fl2==0)?"YES":"NO");
    return 0;
    return 0;
}
}