Submission #1690959

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Source Code Expand

import java.util.Scanner;

class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long w=sc.nextLong(),h=sc.nextLong();
		long buf;
		long ans=1;
		if(w<h){
			buf=w;
			w=h;
			h=buf;
		}
		w-=1;h-=1;
		long beki=(long)Math.pow(10, 9)+7;
		for(long i=0;i<h;i++){
			//System.out.println(w+h-i+"  "+(i+1));
			ans=ans*(w+h-i)%beki;
			ans*=calc(i+1,beki-2,beki);
			ans%=beki;
		}
		System.out.println(ans);
	}

	static long calc(long a,long b,long p){
		if(b==0){
			return 1;
		}
		else if(b%2==0){
			long d=calc(a,b/2,p);
			return (d*d)%p;

		}else{
			return (a*calc(a,b-1,p))%p;
		}
	}

}

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