import java.util.Scanner; public class Main{ static long mod=1000000007; static long pow(long a,long x,long m){ if(x==0) return 1; else if(x%2==0) return pow((a*a)%m,x/2,m)%m; else return (a*pow((a*a)%m,x/2,m))%m; } static long rev(long a,long mod){ if(a%mod==0) return 0; return pow(a,mod-2,mod)%mod; } static long nhr(int n,int r){ if(n==0 && r==0) return 1; return ncr(n+r-1,r); } static long ncr(int n,int r){ if(n