foo.cc:3:7: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
    3 | main ()
      |       ^
foo.cc: In function 'int main()':
foo.cc:5:19: warning: variable 'flag' set but not used [-Wunused-but-set-variable]
    5 |  int n,x1,i,max=0,flag=0;
      |                   ^~~~

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