c++ template

#include<bits/stdc++.h>

using namespace std;

template < typename T >
ostream &operator << ( ostream & os, const vector< T > &v ) {
    os << "{";
    typename vector< T > :: const_iterator it;
    for( it = v.begin(); it != v.end(); it++ ) {
        if( it != v.begin() ) os << ", ";
        os << *it;
    }
    return os << "}";
}

typedef vector<int> vi;
#define first f
#define second s
#define deb(x) cerr << #x << " = " << x << endl;