using?namespace?std;
int?dp[101][101],n,m; int?main(){ dp[0][0]=1;scanf("%d%d",&n,&m);
for?(int?i=1;i<=m;i++)
for?(int?j=1;j<=n;j++){ if?(j>=1)?dp[i][j]+=dp[i-1][j-1]; if?(j>=2)?dp[i][j]+=dp[i-1][j-2]; if?(j>=3)?dp[i][j]+=dp[i-1][j-3];?}
printf("%d\n",dp[m][n]);
}