C :

int n,m;
int s(int x)
{    
	if(x<1) 
		return x+n;   
	if(x>n) 
		return x-n;  
	return x;
}
int main()
{   
	int a[31][31],i,j;
	memset(a,0,sizeof(a));
    scanf("%d%d",&n,&m);   
    a[1][2]=a[1][n]=1;
    for (i=2;i<=m;i++)    
        for (j=1;j<=n;j++) 
	        a[i][j]=a[i-1][s(j-1)]+a[i-1][s(j+1)];   
   printf("%d\n",a[m][1]);  
   return 0;
}

C++ :

#include<stdio.h>
#include<iostream>
using namespace std;
int m,n;
int pd(int x)
{
	if(x<1)return x+n;
	if(x>n)return x-n;
	return x;
} 
int main()
{
	int f[31][31]={0},i,j;
	cin>>n>>m;
	f[1][2]=f[1][n]=1;
	for(i=2;i<=m;i++)
	{
		for(j=1;j<=n;j++)
		{
			f[i][j]=f[i-1][pd(j-1)]+f[i-1][pd(j+1)];
		}
	}
	cout<<f[m][1];
	return 0;
}

Pascal :

var
  n,m,i,j:longint;
  f:array[1..33,0..33]of longint;
begin
  //assign(input,'ball.in'); reset(input);
  //assign(output,'ball.out'); rewrite(output);

  readln(n,m);
  f[1,0]:=1;
  for i:=1 to m do
    for j:=1 to n do
      if j=1 then
        f[j,i]:=f[n,i-1]+f[2,i-1]
      else
        if j=n then
          f[j,i]:=f[1,i-1]+f[n-1,i-1]
        else
          f[j,i]:=f[j+1,i-1]+f[j-1,i-1];
  writeln(f[1,m]);

  //close(input);
  //close(output);
end.