/in/foo.c: In function 'main':
/in/foo.c:5:20: warning: unused variable 'ev' [-Wunused-variable]
     int n,m,i,j,sv,ev;
                    ^~
/in/foo.c:5:17: warning: unused variable 'sv' [-Wunused-variable]
     int n,m,i,j,sv,ev;
                 ^~
/in/foo.c:5:15: warning: unused variable 'j' [-Wunused-variable]
     int n,m,i,j,sv,ev;
               ^