/in/foo.c: In function 'main':
/in/foo.c:5:10: warning: statement with no effect [-Wunused-value]
     for(x==0;x<=12;x+=4){
         ~^~~
/in/foo.c:4:9: warning: 'x' may be used uninitialized in this function [-Wmaybe-uninitialized]
     int x,y,z;
         ^