perl -T
my %hash;while(<DATA>){ my($cord,$dist)=split; 
push @{$hash{$cord}},$dist;} 
print join "\n",map { $_."\t\t".(sort {$a <=> $b} @{$hash{$_}})[0] }
sort {$a <=> $b}keys %hash
__DATA__
567         344  
1345        567
2346        78   
3456        67 
3456        789
4678        45    
5349        6
6700        124 
6700        50
8964        560

		
567		344
1345		567
2346		78
3456		67
4678		45
5349		6
6700		50
8964		560