33 lines
775 B
C++
33 lines
775 B
C++
#include <cstdio>
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int main()
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{
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__int64 sum,n,k;
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while(~scanf("%I64d",&n),(n>=0))
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{
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k=n/3;
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if(n%3==0)
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{
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if(k&1)
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sum=((1+k)>>1)*((1+k)>>1)*k*k*27+3*k*k;
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else
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sum=(k>>1)*(k>>1)*(1+k)*(1+k)*27+3*k*k;
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}
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if(n%3==1)
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{
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if(k&1)
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sum=((1+k)>>1)*((1+k)>>1)*k*k*27+n+3*k*k;
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else
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sum=(k>>1)*(k>>1)*(1+k)*(1+k)*27+n+3*k*k;
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}
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if(n%3==2)
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{
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if(k&1)
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sum=((1+k)>>1)*((1+k)>>1)*k*k*27+n+n-1+3*k*k;
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else
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sum=(k>>1)*(k>>1)*(1+k)*(1+k)*27+n+n-1+3*k*k;
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}
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printf("%I64d\n",sum);
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}
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return 0;
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}
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