考虑显然合法当且仅当所有连通块大小为偶数
于是用
维护，每次加入一条边
如果已经联通就断掉环上最长的边
否则连这条边也不会使合法变成不合法的情况
然后枚举最大边看是否能删去，能删则删
#include<bits/stdc++.h>
using namespace std;
#define cs const
#define re register
#define pb push_back
#define pii pair<int,int>
#define ll long long
#define y1 shinkle
#define fi first
#define se second
#define bg begin
cs int RLEN=1<<20|1;
inline char gc(){
static char ibuf[RLEN],*ib,*ob;
(ib==ob)&&(ob=(ib=ibuf)+fread(ibuf,1,RLEN,stdin));
return (ib==ob)?EOF:*ib++;
}
inline int read(){
char ch=gc();
int res=0;bool f=1;
while(!isdigit(ch))f^=ch=='-',ch=gc();
while(isdigit(ch))res=(res+(res<<2)<<1)+(ch^48),ch=gc();
return f?res:-res;
}
inline ll readll(){
char ch=gc();
ll res=0;bool f=1;
while(!isdigit(ch))f^=ch=='-',ch=gc();
while(isdigit(ch))res=(res+(res<<2)<<1)+(ch^48),ch=gc();
return f?res:-res;
}
inline int readstring(char *s){
int top=0;char ch=gc();
while(isspace(ch))ch=gc();
while(!isspace(ch)&&ch!=EOF)s[++top]=ch,ch=gc();
s[top+1]='\0';return top;
}
template<typename tp>inline void chemx(tp &a,tp b){a=max(a,b);}
template<typename tp>inline void chemn(tp &a,tp b){a=min(a,b);}
cs int N=400005;
int n,m;
struct edge{
int u,v,w;
}e[N];
namespace lct{
int cnt;
int son[N][2],fa[N],sz[N],xv[N],vl[N],mx[N],mxp[N],rev[N];
#define lc(u) son[u][0]
#define rc(u) son[u][1]
inline void pushup(int u){
sz[u]=sz[lc(u)]+sz[rc(u)]+xv[u]+(u<=n);
mx[u]=vl[u],mxp[u]=u;
if(lc(u)&&mx[u]<mx[lc(u)])mx[u]=mx[lc(u)],mxp[u]=mxp[lc(u)];
if(rc(u)&&mx[u]<mx[rc(u)])mx[u]=mx[rc(u)],mxp[u]=mxp[rc(u)];
}
inline void pushnow(int u){
rev[u]^=1,swap(lc(u),rc(u));
}
inline void pushdown(int u){
if(!rev[u])return;
if(lc(u))pushnow(lc(u));
if(rc(u))pushnow(rc(u));
rev[u]=0;
}
inline bool isrc(int u){return rc(fa[u])==u;}
inline bool isrt(int u){
return !fa[u]||(lc(fa[u])!=u&&rc(fa[u])!=u);
}
inline void rotate(int v){
int u=fa[v],z=fa[u];
int t=isrc(v);
if(!isrt(u))son[z][isrc(u)]=v;
fa[v]=z;
fa[son[v][t^1]]=u;
son[u][t]=son[v][t^1];
son[v][t^1]=u,fa[u]=v;
pushup(u),pushup(v);
}
int stk[N],top;
inline void splay(int u){
stk[top=1]=u;
for(int v=u;!isrt(v);v=fa[v])stk[++top]=fa[v];
for(int i=top;i;i--)pushdown(stk[i]);
while(!isrt(u)){
if(!isrt(fa[u]))
isrc(u)==isrc(fa[u])?rotate(fa[u]):rotate(u);
rotate(u);
}
}
inline void access(int u){
for(int v=0;u;v=u,u=fa[u]){
splay(u);
if(rc(u))xv[u]+=sz[rc(u)];
if(v)xv[u]-=sz[v],fa[v]=u;
rc(u)=v,pushup(u);
}
}
inline void makert(int u){
access(u),splay(u);
pushnow(u);
}
inline int findrt(int u){
access(u),splay(u);
while(pushdown(u),lc(u))u=lc(u);
splay(u);return u;
}
inline void split(int u,int v){
makert(u),access(v),splay(v);
}
inline void link(int u,int v){
makert(v),access(u),splay(u);
cnt-=sz[u]&1,cnt-=sz[v]&1;
fa[v]=u,xv[u]+=sz[v];
pushup(u),cnt+=sz[u]&1;
}
inline void cut(int u,int v){
split(u,v);
cnt-=sz[v]&1;
fa[lc(v)]=0,lc(v)=0,pushup(u),pushup(v);
cnt+=sz[u]&1,cnt+=sz[v]&1;
}
struct heap{
priority_queue<pii> a,b;
inline void push(pii x){a.push(x);}
inline void erase(pii x){b.push(x);}
inline void pop(){
while(b.size()&&a.top()==b.top())a.pop(),b.pop();
a.pop();
}
inline int size()cs{return a.size()-b.size();}
inline pii top(){
while(b.size()&&a.top()==b.top())a.pop(),b.pop();
return a.top();
}
}q;
inline int insert(int i){
lct::vl[i+n]=lct::mx[i+n]=e[i].w,lct::mxp[i+n]=i+n;
int u=e[i].u,v=e[i].v;
int fg=1;
if(findrt(u)==findrt(v)){
split(u,v);
int ps=mxp[v]-n;
if(e[ps].w>e[i].w){
cut(e[ps].u,ps+n),cut(e[ps].v,ps+n);
q.erase(pii(e[ps].w,ps));
}
else fg=0;
}
if(fg){
link(e[i].u,i+n),link(e[i].v,i+n);
q.push(pii(e[i].w,i));
}
if(cnt)return -1;
while(q.size()){
int i=q.top().se;q.pop();
cut(e[i].u,i+n),cut(e[i].v,i+n);
if(cnt){
link(e[i].u,i+n),link(e[i].v,i+n);
q.push(pii(e[i].w,i));
return e[i].w;
}
}return 0;
}
}
int main(){
#ifdef Stargazer
freopen("lx.in","r",stdin);
#endif
n=read(),m=read(),lct::cnt=n;
for(int i=1;i<=n;i++)lct::sz[i]=1,lct::mxp[i]=i;
for(int i=1;i<=m;i++){
e[i].u=read(),e[i].v=read(),e[i].w=read();
cout<<lct::insert(i)<<'\n';
}return 0;
}