Problem C
Conundrum on the Roof

Image taken from commons.wikimedia.org

Input

The first line of the input contains two integers $d_U,d_N$ satisfying $0\le d_U,d_N\le {10}^9$. $d_U$ is the maximum height Eyleifur will scale upwards in a single step and $d_N$ is the maximum height Eyleifur is the maximum height Eyleifur will scale downwards in a single step. The next line contains two integers $r,c$ satisfying $1\le r,c\le {10}^5$. They will also satisfy $rc\le {10}^5$. Next the input will contain $r$ lines each containing $c$ integers $h_{i,j}$ satisfying $0\le h_{i,j}\le {10}^9$. The numbers $h_{i,j}$ give the height map Eyleifur made of the roof. $h_{1,1}$ is always equal to $0$ and is where Eyleifur climbs up onto the roof and begins his walk towards the satellite dish. The last line of the input contains two integers $D_i,D_j$ satisfying $1\le D_i\le r$ and $1\le D_j\le c$ which give the location of the satellite dish.

Output

Print ‘Kvoldinu er bjargad!’ if Eyleifur can make it to the satellite dish and back to the ladder. If there is no way for Eyleifur to get to the satellite dish and back, print ‘Nu er Eyleifur i bobba!’.

1 2
3 3
0 2 6
1 3 5
2 3 4
3 3

Kvoldinu er bjargad!

1 0
2 3
0 5 4
1 2 3
1 2

Nu er Eyleifur i bobba!