/in/foo.c: In function 'main':
/in/foo.c:22:17: warning: unused variable 'n3' [-Wunused-variable]
     int n1, n2, n3;
                 ^~
/in/foo.c:21:31: warning: unused variable 'a3' [-Wunused-variable]
     int a1[10000], a2[10000], a3[10000];
                               ^~