delete pics to save space

1.5023.cpp

@@ -0,0 +1,24 @@
+#include<cstdio>
+#include<algorithm>
+using namespace std;
+typedef long long LL;
+const LL mod=1e9+7;
+int n,m;
+LL ksm(LL a,LL b)
+{
+	LL res=1;
+	for(;b>0;b>>=1,a=a*a%mod) b&1?res=res*a%mod:0;
+	return res;
+}
+const LL v[9]={0,2,12,112,912,7136,56768,453504,3626752};
+int main()
+{
+	scanf("%d%d",&n,&m);
+	if(n>m) swap(n,m);
+	if(n==1) { printf("%lld\n",ksm(2,m)); return 0; }
+	if(n==2) { printf("%lld\n",4*ksm(3,m-1)%mod); return 0; }
+	if(n==m) { printf("%lld\n",v[n]); return 0; }
+	if(n<4) printf("%lld\n",v[n]*ksm(3,m-n)%mod);
+	else printf("%lld\n",(v[n]-ksm(2,n))*3*ksm(3,m-n-1)%mod);
+	return 0;
+}