Submission #1369019

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Source Code Expand

//*
#include <boost/multiprecision/cpp_int.hpp>
typedef boost::multiprecision::cpp_int mint; //*/
#include <bits/stdc++.h>
#define  re(i,j,n) for(li i=(j);i<(n);i++)
#define  rep(i,n) re(i,0,(n))
#define  red(i,n) for(li i=n-1;i>=0;i--)
#define  all(a) begin(a),end(a)
#define  pb(a) push_back(a)
using namespace std;
typedef long int li;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<li> vli;
typedef vector<string> vs;
 
int main()
{
    mint a,b,ans=1;
    cin>>a>>b;
    a--,b--;
    rep(i,a) ans*=(a+b-i);
    rep(i,a) ans/=i+1;
    cout<<ans%1000000007<<endl;
    return 0;
}

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