int* input(){
    int *visited;

    int out = 0;
    int pos = 0;
    int i,j,aux_x,aux_y;
    scanf("%d",&num_pieces);
    visited = (int*)malloc(num_pieces*sizeof(int));
    for(i=0;i<num_pieces;i++){
        visited[i] = 1;
    }
    num_pieces = num_pieces ;
    pieces = (int**)malloc(num_pieces*sizeof(int*));
    for(i = 0; i < num_pieces; i++){
        scanf("%d %d",&aux_x,&aux_y);
        for(j=0;j<pos;j++){
            if((aux_x==pieces[j][0] && aux_y==pieces[j][1]) || (aux_y==pieces[j][0] && aux_x==pieces[j][1])){
                visited[j]++;
                out = 1;
                break;
            }
        }
        if(out==0){
            pieces[pos] = (int*) malloc(2*sizeof(int));
            pieces[pos][0] = aux_x;
            pieces[pos][1] = aux_y;
            pos++;
        }
        out=0;
    }
    return visited;
}