Casi B

#include <iostream>
#include <map>
using namespace std;

int main() {
    map<int,int>ma;
    int n,m,a,b,x,y;
    cin>>n>>m>>a>>b;
    for (int i=0;i<m;i++){
        cin>>x>>y;
        ma[x]++;
        ma[y]++;
    }
    int ans=0;
    for (int i=1;i<=n;i++){
        if(ma[i]>=a && ma[i]<(n-b))
            ans++;
    }
    cout<<ans<<endl;
    return 0;
}