function City(i, n, u, w) {
	this.i = i;
	this.n = n;
	this.u = u;
	this.w = w;
}

function vector() {
	this.a = new Array(); 
}

function _push_back(o) {
	this.a[o.i] = o;
}

function _find(n) {
	for(i=0;i<this.a.length;i++) {
		if (this.a[i] == null) 
			continue;
		else if(this.a[i].n == n)
			return this.a[i];
	}
	
	return null;
}

vector.prototype.push_back=_push_back;
vector.prototype.find=_find;

var v = new vector();