foo.c: In function 'main':
foo.c:8:18: warning: implicit declaration of function 'sqrt' [-Wimplicit-function-declaration]
    8 |       for(j=2;j<=sqrt(i);j++)
      |                  ^~~~
foo.c:8:18: 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 main()
foo.c:13:12: warning: incompatible implicit declaration of built-in function 'sqrt'
   13 |       if(j>sqrt(i))
      |            ^~~~
foo.c:13:12: note: include '<math.h>' or provide a declaration of 'sqrt'
foo.c:5:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    5 |     scanf("%d",&a);
      |     ^~~~~~~~~~~~~~

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