19 lines
195 B
C++
19 lines
195 B
C++
#include<iostream>
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using namespace std;
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int main()
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{
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int n;
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cin>>n;
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long long ans=0;
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int i;
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for(i=1;n-i>=0;i++)
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{
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ans+=i*i;
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n-=i;
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}
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if(n>0) ans+=n*i;
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cout<<ans<<endl;
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return 0;
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}
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