#include #include using namespace std; typedef vector vi; typedef long long ll; const ll mod=1e9+7; int n; vi a,b; ll f(int x,int y){ for(int i=0;i>n; a=b=vi(n); for(int i=0;i>a[i]; a[i]--; } for(int i=0;i>b[i]; b[i]--; } ll res=0; for(int i=0;i