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using namespace std;
typedef long long ll;
const ll mod=998244353;
const int maxn=1e6+50;
const ll inf=0x3f3f3f3f3f3f3f3fLL;
struct {
int from,to,cap,flow;
Edge(int u,int v,int c,int f)
:from(u),to(v),cap(c),flow(f){}
bool operator<(const Edge& a)const{
return from<a.from||(from==a.from&&to<a.to);
}
};
struct Dinic{
int n,m,s,t;
vector<Edge>edges;
vector<int>G[maxn];
bool vis[maxn];
int d[maxn];
int cur[maxn];
void init(int n){
this->n=n;
for(int i=0;i<n;i++)G[i].clear();
edges.clear();
}
void ClearFlow(){
for(int i=0;i<edges.size();i++)edges[i].flow=0;
}
void AddEdge(int from,int to,int cap){
edges.push_back(Edge(from,to,cap,0));
edges.push_back(Edge(to,from,0,0));
m=edges.size();
G[from].push_back(m-2);
G[to].push_back(m-1);
}
bool BFS(){
memset(vis,0,sizeof(vis));
memset(d,0,sizeof(d));
queue<int>q;
q.push(s);
d[s]=0;
vis[s]=1;
while(!q.empty()){
int x=q.front();
q.pop();
for(int i=0;i<G[x].size();i++){
Edge& e=edges[G[x][i]];
if(!vis[e.to]&&e.cap>e.flow){
vis[e.to]=1;
d[e.to]=d[x]+1;
q.push(e.to);
}
}
}
return vis[t];
}
int DFS(int x,int a){
if(x==t||a==0)return a;
int flow=0,f;
for(int &i=cur[x];i<G[x].size();i++){
Edge& e=edges[G[x][i]];
if(d[x]+1==d[e.to]&&(f=DFS(e.to,min(a,e.cap-e.flow)))>0){
e.flow+=f;
edges[G[x][i]^1].flow-=f;
flow+=f;
a-=f;
if(a==0)break;
}
}
return flow;
}
int Maxflow(int s,int t){
this->s=s;this->t=t;
int flow=0;
while(BFS()){
memset(cur,0,sizeof(cur));
flow+=DFS(s,inf);
}
return flow;
}
vector<int>Mincut(){
vector<int>ans;
for(int i=0;i<edges.size();i++){
Edge& e=edges[i];
if(vis[e.from]&&!vis[e.to]&&e.cap>0)ans.push_back(i);
}
return ans;
}
void Reduce(){
for(int i=0;i<edges.size();i++)edges[i].cap-=edges[i].flow;
}
}g;
int main()
{
int n,e,c,kase=0;
while(scanf("%d%d%d",&n,&e,&c)==3&&n){
g.init(n);
while(e--){
int a,b,c;
scanf("%d%d%d",&a,&b,&c);
g.AddEdge(a-1,b-1,c);
}
int flow=g.Maxflow(0,n-1);
printf("Case %d: ",++kase);
if(flow>=c)printf("possiblen");
else{
vector<int>cut=g.Mincut();
g.Reduce();
vector<Edge>ans;
for(int i=0;i<cut.size();i++){
Edge& e=g.edges[cut[i]];
e.cap=c;
g.ClearFlow();
if(flow+g.Maxflow(0,n-1)>=c)ans.push_back(e);
e.cap=0;
}
if(ans.empty())printf("not possiblen");
else{
sort(ans.begin(),ans.end());
printf("possible option:(%d,%d)", ans[0].from+1, ans[0].to+1);
for(int i = 1; i < ans.size(); i++)
printf(",(%d,%d)", ans[i].from+1, ans[i].to+1);
printf("n");
}
}
}
return 0;
}
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