foo.cc: In function 'int main()':
foo.cc:13:19: error: 'sprt' was not declared in this scope
   13 |   for (int i=2;i<=sprt(n);i++)
      |                   ^~~~
foo.cc:17:3: error: 'flag' was not declared in this scope
   17 |   flag=1;
      |   ^~~~
foo.cc:21:9: error: 'flag' was not declared in this scope
   21 |   if(1==flag)
      |         ^~~~
foo.cc:5:14: warning: unused variable 'f' [-Wunused-variable]
    5 |  long long n,f=0;
      |              ^

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