BigFungus.pas

program fungus;
const
  maxn = 110;
  iMod = 1000000007;
  moves : array[1..4, 1..2] of Integer = ((1,0),(0,1),(-1,0),(0,-1));
var
  iArr : array[0..maxn] of array[0..maxn] of array[0..1] of int64;
  k, n, m, i, j, cur : integer;
  curX, curY : integer;
  iAns, iTotal : int64;

begin

    // Do not focus on the entire solution, just take note of how the various structures are implemented

  Read(k);
  Read(n);
  Read(m);

  iArr[1][1][1] := 1;
  iArr[1][1][0] := 1;

  while (k > 0) do
    begin

      iAns := 0;

      for I := 1 to n do
        for j := 1 to m do
            begin
              iTotal := 0;
              for cur := 1 to 4 do
                begin
                  curX := i + moves[cur][1];
                  curY := j + moves[cur][2];

                  if (curX < 1) or (curX > n) then continue;
                  if (curY < 1) or (curY > m) then continue;

                  if (moves[cur][1] = 1) or (moves[cur][2] = 1) then
                    begin
                      iTotal := iTotal + (iArr[curX][curY][1] mod iMod);
                    end
                  else
                    begin
                      iTotal := iTotal + (iArr[curX][curY][0] mod iMod);
                    end;
                end;

              iArr[i][j][0] := iArr[i][j][1];
              iArr[i][j][1] := iArr[i][j][1] + (iTotal mod iMod);
              iAns := iAns + iArr[i][j][1];
            end;

      Dec(k);
    end;

  Writeln(iAns mod iMod);
end.