===INPUT===
8 12 5 6
1 1 0 0 0 0 1 0 0 0 0 1
1 0 0 0 1 1 0 1 0 0 1 1
0 0 1 0 0 0 0 0 0 0 0 0
1 0 0 0 0 0 1 0 0 1 0 1
1 0 0 1 0 0 0 0 0 1 0 0 
1 0 1 0 1 0 0 0 1 0 1 0
0 0 0 0 1 0 1 0 0 0 0 0
1 0 1 1 0 1 1 1 0 1 0 1
===OUTPUT===
7
===END===