38 lines
809 B
C++
38 lines
809 B
C++
#include<cstdio>
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#include<cstring>
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#include<algorithm>
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using namespace std;
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const int maxn=40000;
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int T;
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int n;
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long long a[100],x,cnt;
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long long vis[maxn];
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int main()
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{
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scanf("%d",&T);
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while(T--){
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memset(vis,0,sizeof(vis));
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scanf("%d",&n);
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for(int i=0;i<n;i++)
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scanf("%I64d",&a[i]);
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cnt=0;
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for(int i=0;i<n;i++){
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x=a[i];
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for(long long j=2;j*j<=x;j++){
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while(x%j==0){
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x/=j;
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vis[cnt++]=j;
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}
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}
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if(x>1)
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vis[cnt++]=x;
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}
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sort(vis,vis+cnt);
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if(cnt<2)
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printf("-1\n");
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else
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printf("%I64d\n",vis[0]*vis[1]);
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}
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return 0;
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}
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