#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
typedef long long LL;
const int N=1e6;
int n,m,vis[N+10],head[N+10],tot;
LL cnt1=0,cnt2=0,cnt3=0;
struct data {
int next,num;
}edge[N+10];
void Add(int u,int v) {
edge[++tot].next=head[u];
edge[tot].num=v;
head[u]=tot;
}
int dfs(int x,int k) {
if (vis[x]!=-1&&vis[x]!=k) return 0;
if (vis[x]!=-1) return 1;
vis[x]=k;
int ans=1;
for (int i=head[x];i!=-1;i=edge[i].next) {
int kx=edge[i].num;
int nowk=dfs(kx,k^1);
if (nowk==0) ans=0;
}
return ans;
}
int main() {
memset(head,-1,sizeof(head));
scanf("%d%d",&n,&m);
for (int i=1;i<=m;i++) {
int u,v;
scanf("%d%d",&u,&v);
Add(u,v);
Add(v,u);
}
memset(vis,-1,sizeof(vis));
for (int i=1;i<=n;i++) {
if (vis[i]!=-1) continue;
if (head[i]==-1) {
cnt3++;
continue;
}
int k=dfs(i,1);
if (k==0) cnt1++;
else cnt2++;
}
LL ans=(LL)n*n-(n-cnt3)*(n-cnt3);
ans+=cnt1*cnt1+cnt1*cnt2*2+cnt2*cnt2*2;
printf("%lld\n",ans);
return 0;
}
./Main.cpp: In function ‘int main()’:
./Main.cpp:32:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
scanf("%d%d",&n,&m);
^
./Main.cpp:35:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
scanf("%d%d",&u,&v);
^