#include <iostream>
#include <algorithm>

using namespace std;

struct rect
{
    int w;
    int h;
};

bool sortRect(const rect &r1, const rect &r2)
{
    if(r1.w != r2.w)
    {
        return r1.w > r2.w;
    }
    else
    {
        return r1.h > r2.h;
    }
}

int main()
{
    rect rects[6];
    while(cin >> rects[0].w && cin >> rects[0].h)
    {
        if(rects[0].w < rects[0].h)
        {
            swap(rects[0].w, rects[0].h);
        }

        for(int i = 1 ; i <= 5;++i)
        {
            cin >> rects[i].w >> rects[i].h;
            if(rects[i].w < rects[i].h)
            {
                swap(rects[i].w, rects[i].h);
            }
        }

        sort(rects, rects + 6, sortRect );
        if(rects[0].w != rects[1].w || rects[0].h != rects[1].h ||
           rects[2].w != rects[3].w || rects[2].h != rects[3].h ||
           rects[4].w != rects[5].w || rects[4].h != rects[5].h
           )
        {
            printf("IMPOSSIBLE\n");
        }
        else if(rects[0].w != rects[2].w || rects[0].h != rects[4].w || rects[2].h != rects[4].h)
        {
            printf("IMPOSSIBLE\n");
        }
        else
        {
            printf("POSSIBLE\n");
        }
    }
    return 0;
}