// LLP-Edge-Relaxation: ensure-based shortest path via edge relaxation.

class LLPEdgeRelaxation {
  void LLPEdgeRelaxation(set<int>[] pre, int[][] w) {
    int[] G = maxint;
    G[s] = 0;
    ensure (j) : G[j] <= min i in pre[j] : G[i] + w[i][j];
  }
}