foo.cc: In function 'bool spfa(int)':
foo.cc:21:48: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
   21 |     for(int i=1;i<=n;++i) d[i]=inf,inq[i]=nc[i]=0;
      |                                           ~~~~~^~
foo.cc:22:27: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
   22 |     q[tail]=s;inq[s]=nc[s]=1;lop(tail);d[s]=0;
      |                      ~~~~~^~

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