Red Huang

//====================================================================||  
//                                                                    ||  
//                                                                    ||  
//                         Author : GCA                               ||  
//                  6AE7EE02212D47DAD26C32C0FE829006                  ||  
//====================================================================||  
#include <iostream>  
#include <cstdio>  
#include <cstring>  
#include <algorithm>  
#include <cmath>  
#include <climits>  
#include <vector>  
#include <set>  
#include <map>  
#include <queue>  
#include <cctype>  
#include <utility>  
using namespace std;  
#ifdef ONLINE\_JUDGE  
#define ll "%lld"  
#else  
#define ll "%I64d"  
#endif  
typedef unsigned int uint;  
typedef long long int Int;  
#define Set(a,s) memset(a,s,sizeof(a))  
#define Write(w) freopen(w,"w",stdout)  
#define Read(r) freopen(r,"r",stdin)  
#define Pln() printf("\\n")  
#define I\_de(x,n)for(int i=0;i<n;i++)printf("%d ",x\[i\]);Pln()  
#define De(x)printf(#x"%d\\n",x)  
#define For(i,x)for(int i=0;i<x;i++)  
#define CON(x,y) x##y  
#define Pmz(dp,nx,ny)for(int hty=0;hty<ny;hty++){for(int htx=0;htx<nx;htx++){\\  
    printf("%d ",dp\[htx\]\[hty\]);}Pln();}  
#define M 1000005  
#define PII pair<int,int\>  
#define PB push\_back  
#define oo INT\_MAX  
#define Set\_oo 0x3f  
#define Is\_debug true  
#define debug(...) if(Is\_debug)printf("DEBUG: "),printf(\_\_VA\_ARGS\_\_)  
#define FOR(it,c) for(\_\_typeof((c).begin()) it=(c).begin();it!=(c).end();it++)  
#define eps 1e-6  
bool xdy(double x,double y){return x>y+eps;}  
bool xddy(double x,double y){return x>y-eps;}  
bool xcy(double x,double y){return x<y-eps;}  
bool xcdy(double x,double y){return x<y+eps;}  
int min3(int x,int y,int z){  
    int tmp=min(x,y);  
    return min(tmp,z);  
}  
int max3(int x,int y,int z){  
    int tmp=max(x,y);  
    return max(tmp,z);  
}  
struct edge{  
    int x,y,w;  
}edges\[M\];  
int n,m;  
int p\[M\];  
int rank\[M\];  
bool cmp(edge a,edge b){  
    return a.w<b.w;  
}  
void init(){  
    for(int i=0;i<n;i++){  
        rank\[i\]=0;  
        p\[i\]=i;  
    }  
}  
int getf(int x){  
    if(x!=p\[x\])p\[x\]=getf(p\[x\]);  
    return p\[x\];  
}  
void \_union(int x,int y){  
  
    if(rank\[x\]>rank\[y\])p\[y\]=x;  
    else{  
        p\[x\]=y;  
        if(rank\[x\]==rank\[y\])rank\[y\]++;  
    }  
  
}  
void solve(){  
    sort(edges,edges+m,cmp);  
    int mx=0;  
    int cm=0;  
    for(int i=0;i<m;i++){  
        int x=edges\[i\].x;  
        int y=edges\[i\].y;  
        int w=edges\[i\].w;  
        int fx=getf(x);  
        int fy=getf(y);  
        if(fx!=fy){  
            \_union(fx,fy);  
            cm++;  
            mx=max(mx,w);  
        }  
    }  
    if(cm+1<n)printf("IMPOSSIBLE\\n");  
    else printf("%d\\n",mx);  
}  
int main() {  
    ios\_base::sync\_with\_stdio(0);  
    while(~scanf("%d%d",&n,&m)&&n+m){  
        init();  
        for(int i=0;i<m;i++){  
            scanf("%d%d%d",&edges\[i\].x,&edges\[i\].y,&edges\[i\].w);  
        }  
        solve();  
    }  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
}