#include #include using namespace std; pair v[100010]; int n,m,i,a,b; int main() { cin>>n>>m; for( i = 1 ; i <= n ; i++ ) cin>>v[ i ].first>>v[ i ].second; sort( v + 1 , v + n + 1 ); for( i = 1 ; i <= n / 2 ; i++ ) a += v[ i ].second, b += v[ i + n / 2 ].first; cout<