foo.cc: In function 'long long int Dijkstra(long long int, long long int)':
foo.cc:30:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i=0;i<edge[u].size();i++) {
                     ~^~~~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:44:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld%lld",&a,&b);
     ~~~~~^~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务