var
n,m,i,j:longint;
f:array[0..30,0..30] of longint;
begin
readln(n,m);
f[1,0]:=1;
for i:=2 to n-1 do begin
for j:=1 to m do begin
f[1,j]:=f[2,j-1]+f[n,j-1];
f[i,j]:=f[i-1,j-1]+f[i+1,j-1];
f[n,j]:=f[n-1,j-1]+f[1,j-1];
end;
end;
writeln(f[1,m]);
end. f的意思是第j次传球传到第i人手中的种数