#include <iostream>
#include <map>
#include <algorithm>
using namespace std;
int main()
{
int data[]={1, 2, 3, 4, 1, 2, 3, 4, 1, 1, 2, 5, 12, 5};
map<int,unsigned> tb;
for(size_t i=0;i<sizeof(data)/sizeof(*data);++i) ++tb[data[i]];
for(map<int,unsigned>::iterator i=tb.begin();i!=tb.end();++i) if(i->second==2) cout<<i->first<<endl;
return 0;
}
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