My solution: http://pastebin.com/BVfebbpv

I used such algorithm:
1) sort of each point (it seems to work correctly on tests with same coordinates)
2) walk through sorted array of points, making dp on every segment with two variables (maxi and maxv) to indicate maximum value we can reach in this segment and id of inside segment, corresponding to this maaximal value

I tried almost all tests from topics and lots, invented by myself and can't get what's wrong with my solution.

Try
3
1 6
3 9
3 5

try this
8
1 10
2 3
4 5
6 7
8 9
20 30
21 29
22 28

answer
3
8 7 6

I also had WA#3, but this test is AC. My solution used BFS. Please, help me! Thanks!

#pragma comment(linker,"/STACK:8000000")
#include <stdio.h>

int loading(int &N,int** (&M)){
    int *Left,*Right;
    scanf("%d",&N);
    if(N==0) {printf("%d",0); return -1;}
    Left=new int[N]; Right=new int[N];
    int tmpL,tmpR;
    for(int i=0;i<N;++i) {scanf("%d %d",&tmpL,&tmpR); /*if(tmpR<tmpL) {int tmp=tmpR; tmpR=tmpL; tmpL=tmp;}*/ Left[i]=tmpL; Right[i]=tmpR;}

    M=new int*[N];
    for(int i=0;i<N;++i) {M[i]=new int[N]; for(int j=0;j<N;++j) M[i][j]=0;}

    //i-ый отрезок вложен в j-ый
    for(int i=0;i<N;++i) for(int j=0;j<N;++j) if(Left[j]<Left[i] && Right[i]<Right[j]) {M[i][j]=1; M[j][i]=-1;}

    delete[] Left;delete[] Right;
    return 0;
}


int doing(int &N,int **(&M),int *(&Last),int &posBiggestWeight,int &BiggestWeight){
    Last=new int[N];
    int *Weight=new int[N];
    for(int i=0;i<N;++i) {Last[i]=-1; Weight[i]=0;}

    //Поиск отрезков, которые ни во что не вложены
    int *Roots=new int[N],iCountRoots=0;
    for(int i=0;i<N;++i){
        bool isNotRoot=true;
        for(int j=0;j<N && isNotRoot;++j) if(M[i][j]==1) isNotRoot=false;
        if(!isNotRoot){
            Roots[iCountRoots++]=i;
        }
    }

    //Перебор всех вложеных
    for(int k=0;k<iCountRoots;++k){
        int NeedVisit[1000000],cntNVisit=0;
        NeedVisit[cntNVisit++]=Roots[k]; Weight[Roots[k]]=0;
        while(cntNVisit>0){
            int tekVertex=NeedVisit[--cntNVisit],tekWeight=Weight[tekVertex],newWeight=tekWeight+1;
            for(int j=0;j<N;++j) if(M[tekVertex][j]==1 && newWeight>=Weight[j]){
                NeedVisit[cntNVisit++]=j; Weight[j]=newWeight; Last[j]=tekVertex;
            }
        }
    }
    //поиск максимального веса
    BiggestWeight=-2; posBiggestWeight=-1;
    for(int i=0;i<N;++i) if(Weight[i]>BiggestWeight){
        posBiggestWeight=i; BiggestWeight=Weight[i];
    }
    delete[] Weight;
    return 0;
}

int saveing(int &N,int* (&Last),int &posBiggestWeight,int &BiggestWeight){
    int *Answer=new int[BiggestWeight+1],pos=posBiggestWeight;
    int indAnswer=BiggestWeight;
    while(pos!=-1){
        Answer[indAnswer--]=pos+1; pos=Last[pos];
    }
    printf("%d\n",BiggestWeight+1);
    for(int i=0;i<BiggestWeight;++i) printf("%d ",Answer[i]); printf("%d\n",Answer[BiggestWeight]);
    delete[] Answer;
    return 0;
}

int main(){
    int N,**M,*Last,posBiggestWeight=0,BiggestWeight=0;
    int res=loading(N,M);
    if(res==-1) return 0;
    doing(N,M,Last,posBiggestWeight,BiggestWeight);
    saveing(N,Last,posBiggestWeight,BiggestWeight);

    delete[] Last;
    for(int i=0;i<N;++i) delete[] M[i];
    delete[] M;

    return 0;
}