foo.c: In function 'prime':
foo.c:6:8: warning: implicit declaration of function 'sqrt' [-Wimplicit-function-declaration]
    6 |  int j=sqrt(n);
      |        ^~~~
foo.c:6:8: warning: incompatible implicit declaration of built-in function 'sqrt'
foo.c:2:1: note: include '<math.h>' or provide a declaration of 'sqrt'
    1 | #include<stdio.h>
  +++ |+#include <math.h>
    2 | int prime(int n)
foo.c: In function 'main':
foo.c:33:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   33 |  scanf("%d",&x);
      |  ^~~~~~~~~~~~~~

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