// pare ok :)
#include <stdio.h>

#define in "patratel.in"
#define out "patratel.out"
#define dim 4001

bool a[dim][dim];
int sol[dim][dim];
int s, n;

int minim(int a, int b) { return a < b ? a : b; }

int main()
{
    int total=0;
    freopen(in,"r",stdin);
    freopen(out,"w",stdout);
    
    scanf("%d%d",&n,&s);
    
    n = dim-1;
    
    for ( int i = 1; i <= n; i++ )
    {
        for ( int j = 1; j <= n; j++ )
        {
            //scanf("%d",&a[i][j]);
            a[i][j] = 1;
            sol[i][j] = 1;
        }
    }
    
  /*  for ( int i = 1; i <= n; i++ )
    {
        for ( int j = 1; j <= n; j++ )
        {
            if ( a[i][j] == 1 ) 
            {
                 sol[i][j] = 0; 
                 continue;
            }
            
            sol[i][j] = minim(sol[i-1][j], minim(sol[i-1][j-1],sol[i][j-1])) + 1;
            if ( sol[i][j] == s ) 
            {
                 sol[i][j] -= 1;
                 total+=1;
                 
            }
        }
    }*/
    
    printf("%d", total);
}