The given problem is a pretty basic dynamic problem.It can be solved using counting principle and dynamic programming. But I am receiving incorrect answer for this approach which seems logically correct to me.It will be kind of you if you could help me out.

#include<bits/stdc++.h>
using namespace std;
int solve(int A) {
      long long int mod=1e9+7;
      int dp[A][3][4]={0};

    for(int j=0;j<4;j++)
    dp[0][0][j]=1;
    for(int i=0;i<A;i++)
    {
        for(int j=0;j<3;j++)
        {
           for(int k=0;k<4;k++)
           {
               for(int p=0;p<4;p++)
               {
				   if(p!=k)
               {if(j>=1)
				   dp[i][j][k]+=dp[i][j-1][p];
				   dp[i][j][k]%=mod;
				   if(i>=1)
                dp[i][j][k]+=dp[i-1][j][p];
                dp[i][j][k]%=mod;
                }
               }
           }
        }
    }
    return (dp[A-1][2][0]+dp[A-1][2][1]+dp[A-1][2][2]+dp[A-1][2][3])%mod;
}

int main()
{
	int a=2;
	cout<<solve(2);
   }