17 lines
323 B
C++
17 lines
323 B
C++
#include<cstdio>
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#include<algorithm>
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using namespace std;
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int main()
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{
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#ifdef local
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freopen("pro.in","r",stdin);
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#endif
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int n,m;
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scanf("%d%d",&n,&m);
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if(n>m) swap(n,m);
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if(n==1) printf("%d",(m/6*3+max(m%6-3,0))*2);
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else if(n==2) printf("%d",m==2?0:m==3?4:m==7?12:m*2);
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else printf("%lld",1LL*n*m/2*2);
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return 0;
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}
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