#include<stdio.h> int n,m; long long dfs[31][31]; int main() { scanf("%d %d",&n,&m); dfs[m][1]=1; for(int i=m-1;i>=0;i--) for(int j=1;j<=n;j++) { if(j==1) dfs[i][j]=dfs[i+1][2]+dfs[i+1][n]; if(j==n) dfs[i][j]=dfs[i+1][1]+dfs[i+1][n-1]; if(j!=1&&j!=n) dfs[i][j]=dfs[i+1][j-1]+dfs[i+1][j+1]; } printf("%lld",dfs[0][1]); return 0; } /************************************************************** Problem: 1801 User: admin Language: C Result: Accepted Time:54 ms Memory:1152 kb ****************************************************************/