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| #include<algorithm>
#include<iostream>
#include<iomanip>
#include<cstring>
#include<cstdlib>
#include<vector>
#include<cstdio>
#include<cmath>
#include<queue>
using namespace std;
inline const int Get_Int() {
int num=0,bj=1;
char x=getchar();
while(x<'0'||x>'9') {
if(x=='-')bj=-1;
x=getchar();
}
while(x>='0'&&x<='9') {
num=num*10+x-'0';
x=getchar();
}
return num*bj;
}
const int maxn=100005;
vector<int>edges[maxn];
int n,m,step=0,BCC=0,top=0,ans=0,father[maxn],Degree[maxn],Lowlink[maxn],Dfn[maxn],InStack[maxn],Belong[maxn];
void AddEdge(int x,int y) {
edges[x].push_back(y);
}
void Tarjan(int Now) {
step++;
Lowlink[Now]=Dfn[Now]=step;
InStack[++top]=Now;
for(int i=0; i<edges[Now].size(); i++) {
int Next=edges[Now][i];
if(father[Now]==Next)continue;
if(!Dfn[Next]) {
father[Next]=Now;
Tarjan(Next);
Lowlink[Now]=min(Lowlink[Now],Lowlink[Next]);
} else Lowlink[Now]=min(Lowlink[Now],Dfn[Next]);
}
if(Lowlink[Now]==Dfn[Now]) {
BCC++;
int y;
do {
y=InStack[top--];
Belong[y]=BCC;
} while(Now!=y);
}
}
int main() {
n=Get_Int();
m=Get_Int();
for(int i=1; i<=m; i++) {
int x=Get_Int(),y=Get_Int();
AddEdge(x,y);
AddEdge(y,x);
}
Tarjan(1);
for(int Now=1; Now<=n; Now++)
for(int i=0; i<edges[Now].size(); i++) {
int Next=edges[Now][i];
if(Belong[Now]!=Belong[Next])Degree[Belong[Next]]++;
}
for(int i=1; i<=BCC; i++)if(Degree[i]==1)ans++;
printf("%d\n",(ans+1)/2);
return 0;
}
|
