/in/foo.c: In function 'main':
/in/foo.c:43:6: warning: implicit declaration of function 'memset' [-Wimplicit-function-declaration]
      memset(a,0,sizeof(a));
      ^~~~~~
/in/foo.c:43:6: warning: incompatible implicit declaration of built-in function 'memset'
/in/foo.c:43:6: note: include '<string.h>' or provide a declaration of 'memset'
/in/foo.c:41:13: warning: unused variable 'z' [-Wunused-variable]
     int x,y,z;
             ^
/in/foo.c:41:11: warning: unused variable 'y' [-Wunused-variable]
     int x,y,z;
           ^
/in/foo.c:41:9: warning: unused variable 'x' [-Wunused-variable]
     int x,y,z;
         ^
/in/foo.c:40:15: warning: unused variable 'p' [-Wunused-variable]
     int i,j,k,p;
               ^
/in/foo.c:40:13: warning: unused variable 'k' [-Wunused-variable]
     int i,j,k,p;
             ^
/in/foo.c:40:11: warning: unused variable 'j' [-Wunused-variable]
     int i,j,k,p;
           ^