#include <iostream>
#include <iterator>
#include <vector>
#include <algorithm>
bool isNumber( const std::string& s )
{
for( auto c : s )
{
if( !std::isdigit(c) ) return false;
}
return true;
}
int main() {
std::istream_iterator<std::string> iit(std::cin);
std::vector<std::string> v;
std::copy_if( iit, std::istream_iterator<std::string>(), back_inserter(v), isNumber );
std::ostream_iterator<std::string> oit( std::cout, "\n");
std::copy( v.begin(), v.end(), oit );
return 0;
}
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