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| #include<cstdio>
#include<vector>
#include<cstring>
using namespace std;
int n,m;
int min1=99999999;
vector < int > a[99999];
int ans;
int ans1;
int f[99999];
int flag;
int dfs(int x)
{
if(flag==1) return 0;
for(int i=0;i<a[x].size();i++)
{
if(f[a[x][i]]==f[x])
{
flag=1;return 0;
}
else if(!f[a[x][i]])
{
if(f[x]==1) f[a[x][i]]=2,ans1++;
else if(f[x]==2) f[a[x][i]]=1,ans++;
dfs(a[x][i]);
}
}
return 0;
}int tot=0;
int main()
{
scanf("%d%d",&n,&m);
for(int i=1;i<=m;i++)
{
int x,y;
scanf("%d%d",&x,&y);
a[x].push_back(y);
a[y].push_back(x);
}
for(int i=1;i<=n;i++)
{ans=0;
ans1=0;
if(!f[i])
{
ans++;//ans1++;
f[i]=1;
//flag[i]=1;
dfs(i);
tot+=min(ans,ans1);
}
//min1=min(tot,min1);
}
if(flag==1)printf("Impossible");
else printf("%d",tot);
return 0;
}
|
