D - Flip Cards

#include <iostream>
using namespace std;

long long v[200001][3];
int a[200001],b[200001];

#define MOD 998244353

int main()
{
    int n,i;
    cin>>n;
    for(i=0;i<n;i++)
        cin>>a[i]>>b[i];
    v[0][1]=v[0][2]=1;
    for(i=1;i<n;i++){
        if(a[i-1]!=a[i]){
            v[i][1]=(v[i][1]+v[i-1][1])%MOD;
        }
        if(a[i-1]!=b[i]){
            v[i][2]=(v[i][2]+v[i-1][1])%MOD;
        }
        if(b[i-1]!=b[i]){
            v[i][2]=(v[i][2]+v[i-1][2])%MOD;
        }
        if(b[i-1]!=a[i]){
            v[i][1]=(v[i][1]+v[i-1][2])%MOD;
        }

    }
    cout<<(v[n-1][1]+v[n-1][2])%MOD;
    return 0;
}