1 #include<cstdio>
2 #include<map>
3 #include<iostream>
4 #include<vector>
5 #include<algorithm>
6 #define ull unsigned long long
7 using namespace std;
8 const int N=1000010;
9 int n,m;
10 vector<int>s[N];
11 map<ull,int>mp;
12 map<ull,int>::iterator it;
13 int main(){
14 freopen("bzoj4264.in","r",stdin);
15 freopen("bzoj4264.out","w",stdout);
16 scanf("%d%d",&n,&m);
17 for(int i=1,x,y;i<=m;i++){
18 scanf("%d%d",&x,&y);
19 s[x].push_back(y);
20 s[y].push_back(x);
21 }
22 ull ans=0;
23 for(int i=1;i<=n;i++){
24 sort(s[i].begin(),s[i].end());
25 unique(s[i].begin(),s[i].end());
26 ull x=0;
27 for(int j=0;j<(int)s[i].size();j++){
28 x = x * (ull)1234567891 + s[i][j];
29 }
30 mp[x]++;
31 }
32 for(it = mp.begin();it!=mp.end();it++){
33 ans += (ull)it -> second * (it -> second - 1) / 2;
34 }
35 mp.clear();
36 for(int i=1;i<=n;i++){
37 s[i].push_back(i);
38 sort(s[i].begin(),s[i].end());
39 unique(s[i].begin(),s[i].end());
40 ull x=0;
41 for(int j=0;j<(int)s[i].size();j++){
42 x = x * (ull)1234567891 + s[i][j];
43 }
44 mp[x]++;
45 }
46 for(it = mp.begin();it!=mp.end();it++){
47 ans += (ull)it -> second * (it -> second - 1) / 2;
48 }
49 cout << ans << endl;
50 return 0;
51 }
bzoj4264