/in/foo.c: In function 'main':
/in/foo.c:6:21: warning: unused variable 'b' [-Wunused-variable]
    6 |         int a[i][j],b[i][j];
      |                     ^
/in/foo.c:6:9: warning: 'j' is used uninitialized [-Wuninitialized]
    6 |         int a[i][j],b[i][j];
      |         ^~~
/in/foo.c:4:15: note: 'j' was declared here
    4 |         int i,j,n;
      |               ^
/in/foo.c:6:9: warning: 'i' is used uninitialized [-Wuninitialized]
    6 |         int a[i][j],b[i][j];
      |         ^~~
/in/foo.c:4:13: note: 'i' was declared here
    4 |         int i,j,n;
      |             ^