foo.cc: In function 'int main()':
foo.cc:31:9: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
   if(num=n-1)break;
      ~~~^~~~
foo.cc:40:40: warning: format '%lf' expects argument of type 'double', but argument 2 has type 'int' [-Wformat=]
  printf("Need %.2lf miles of cable",ans);
                                        ^

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