#include<iostream>#include<sstream>#include<fstream>#include<vector>#include<list>#include<deque>#include<queue>#include<stack>#include<map>#include<set>#include<bitset>#include<algorithm>#include<cstdio>#include<cstdlib>#include<cstring>#include<cctype>#include<cmath>#include<ctime>using namespace std;const double eps(1e-8);typedef long long lint;#define clr(x) memset( x , 0 , sizeof(x) )#define sz(v) ((int)(v).size())#define rep(i, n) for (int i = 0; i < (n); ++i)#define repf(i, a, b) for (int i = (a); i <= (b); ++i)#define repd(i, a, b) for (int i = (a); i >= (b); --i)#define clrs( x , y ) memset( x , y , sizeof(x) )bool bj[110000] ;int jl[110000] ;bool mul[110000] ;int s[110000];int e[110000];int first[110000],last[110000],vv[110000];int n , m , ans , top ,dtop;void insert(int a,int b ){dtop++;e[dtop]=b;if (first[a]==0)last[a]=first[a]=dtop;else {vv[last[a]]=dtop;last[a]=dtop;}}void dfs( int i ) { if ( bj[i] ) return ; bj[i] = top ; if ( s[i] % 2 ) jl[top] ++ ; if ( s[i] > 2 ) { ans ++ ; mul[top] = true ; } for (int j=first[i];j!=0;j=vv[j]) dfs( e[j] ) ;}int solve() { if ( top == 1 ) { return ans + jl[1] / 2 ; } else { repf( i , 1 , top ) { if ( jl[i] == 0 && mul[i]) continue ; if ( jl[i] == 0 ) ans ++ ; else ans += jl[i] / 2 - 1 ; } ans += top ; } return ans ;}int main(){ while ( scanf("%d %d" , &n , &m ) == 2 ) { ans = 0 ;clr(jl);clr(mul);dtop=0; clr(s); clr(e) ; clr(vv) ;clr(first);clr(last); int have = n ; repf( i , 1 , m ) { int a , b ; scanf("%d %d" , &a ,&b ) ; if ( a == 0 ) a = ++have ; if ( b == 0 ) b = ++have ; s[a]++;s[b]++; insert(a,b); insert(b,a); } n = have ; top = 0 ;clr(bj); repf( i , 1 , n ) { if ( s[i] == 0 ) continue ; if ( !bj[i] ) { top ++ ; dfs(i); } } printf("%dn",solve()); }}
