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#include <iostream>
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#include <iomanip>
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using namespace std;
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int main()
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{
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   int n,m,a;
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   cin>>n>>m>>a;
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   long long cnt1=n/a;
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   if(n%a!=0)
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      cnt1++;
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   int cnt2=m/a;
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   if(m%a!=0)
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      cnt2++;
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   cout<<cnt1*cnt2;
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}