#include<iostream>#include<cstdio>#include<cstring>#include<vector>#include<algorithm>using namespace std;#define clr(x,a) memset(x,a,sizeof(x))const int inf = 1012345678;int rd(){int x;scanf("%d",&x); return x;}const int maxn = 200001;const int maxe =1000010;#define sz(x) (int)x.size()#define pb push_back#define L nod<<1#define R nod<<1|1#define lson nod<<1,l,mid#define rson nod<<1|1,mid+1,rint n,m;struct node{int v,w;node(){}node(int aa,int bb){v=aa; w=bb;}}a[maxn];bool cmp1(node a,node b){if(a.v==b.v)return a.w>b.w;return a.v>b.v;}bool cmp2(node a,node b){if(a.v==b.v)return a.w<b.w;return a.v<b.v;}int tr[maxe*4],fd;void find(int nod,int l,int r,int x,int y){if(x<=l && r<=y){fd=max(fd,tr[nod]);return ;}int mid=(l+r)/2;if(x<=mid)find(lson,x,y);if(mid<y)find(rson,x,y);}void insert(int nod,int l,int r,int x,int y,int a){if(x<=l && r<=y){tr[nod]=max(tr[nod],a);return ;}int mid=(l+r)/2;if(x<=mid)insert(lson,x,y,a);if(mid<y)insert(rson,x,y,a);tr[nod]=max(tr[L],tr[R]);}vector<node>vc[maxe];int main(){int i,j,k;while(scanf("%d",&n)!=EOF){int x,y;int maxx=0;for(i=0; i<n; i++){scanf("%d%d",&x,&y);a[i]=node(x,y);maxx=max(maxx,y);}sort(a,a+n,cmp1);int cnt=0;for(i=0; i<n; i++){fd=0;find(1,0,maxx,a[i].w,maxx);fd++;cnt=max(cnt,fd);vc[fd].pb(a[i]);insert(1,0,maxx,a[i].w,a[i].w,fd);}for(i=1; i<=cnt; i++){printf("%d:",sz(vc[i]));sort(vc[i].begin(),vc[i].end(),cmp2);for(j=0; j<sz(vc[i]); j++){printf(" (%d,%d)",vc[i][j].v,vc[i][j].w);}puts("");vc[i].clear();}}}
