foo.c: In function 'main':
foo.c:4:9: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    4 |         scanf("%d",&n);
      |         ^~~~~
foo.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | int main()
foo.c:4:9: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    4 |         scanf("%d",&n);
      |         ^~~~~
foo.c:4:9: note: include '<stdio.h>' or provide a declaration of 'scanf'
foo.c:13:9: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
   13 |         printf("%d", b);
      |         ^~~~~~
foo.c:13:9: note: include '<stdio.h>' or provide a declaration of 'printf'
foo.c:13:9: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
foo.c:13:9: note: include '<stdio.h>' or provide a declaration of 'printf'
foo.c:3:25: warning: unused variable 'a' [-Wunused-variable]
    3 |         int i,n,ret=1,b,a;
      |                         ^
foo.c:3:13: warning: unused variable 'i' [-Wunused-variable]
    3 |         int i,n,ret=1,b,a;
      |             ^

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