131C: The World is a Theatre

Problem Link

||Source Code||

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define fr(i,a,b) for(i=a;i<b;i++)
ll nCr(ll n,ll r)
{
ll res=1,i;
for(i=0;i<r;i++) { res*=(n-i); res/=(i+1); } return res; } int main() { ll n,i,r,t,ans=0; cin>>n>>r>>t;
for(i=4;i<t;i++)
{
ans+=nCr(n,i)*nCr(r,t-i);
}
cout<<ans<<endl;
}

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About waprogramming

I am in CSE,from CUET
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