int main() {
while (true) {
int n, m, source;
double v;
if (scanf("%d %d %d %lf", &n, &m, &source, &v) == -1) break;
--source;
WeightedDirectedGraphAsEdgeList<WeightType> graph(n, m);
for (int i = 0; i < m; ++i) {
int a, b;
double Rab, Cab, Rba, Cba;
scanf("%d %d %lf %lf %lf %lf", &a, &b, &Rab, &Cab, &Rba, &Cba);
--a; --b;
graph.AddEdge(WeightedEdge<WeightType>(a, b, WeightType(Rab, Cab)));
graph.AddEdge(WeightedEdge<WeightType>(b, a, WeightType(Rba, Cba)));
}
CurrencyBellmanFord SSSP(&graph, source, v);
SSSP.Compute();
if (SSSP.ExistNegativeCycle()) {
printf("YES\n");
} else if (SSSP.Distance(source) > v) {
printf("YES\n");
} else {
printf("NO\n");
}
}
return 0;
}
param_type(const IntervalRange& intervals_arg,
const WeightRange& weights_arg)
: _intervals(boost::begin(intervals_arg), boost::end(intervals_arg)),
_weights(boost::begin(weights_arg), boost::end(weights_arg))
{
if(_intervals.size() < 2) {
_intervals.clear();
_intervals.push_back(RealType(0));
_intervals.push_back(RealType(1));
_weights.push_back(WeightType(1));
}
}
param_type(IntervalIter intervals_first, IntervalIter intervals_last,
WeightIter weight_first)
: _intervals(intervals_first, intervals_last)
{
if(_intervals.size() < 2) {
_intervals.clear();
_intervals.push_back(RealType(0));
_intervals.push_back(RealType(1));
_weights.push_back(WeightType(1));
} else {
_weights.reserve(_intervals.size() - 1);
for(std::size_t i = 0; i < _intervals.size() - 1; ++i) {
_weights.push_back(*weight_first++);
}
}
}
param_type(const std::initializer_list<T>& il, F f)
: _intervals(il.begin(), il.end())
{
if(_intervals.size() < 2) {
_intervals.clear();
_intervals.push_back(RealType(0));
_intervals.push_back(RealType(1));
_weights.push_back(WeightType(1));
} else {
_weights.reserve(_intervals.size() - 1);
for(std::size_t i = 0; i < _intervals.size() - 1; ++i) {
RealType midpoint = (_intervals[i] + _intervals[i + 1]) / 2;
_weights.push_back(f(midpoint));
}
}
}
/**
* Constructs a @c param_type object, representing a distribution
* that produces values uniformly distributed in the range [0, 1).
*/
param_type()
{
_weights.push_back(WeightType(1));
_intervals.push_back(RealType(0));
_intervals.push_back(RealType(1));
}
