foo.c: In function 'main':
foo.c:6:13: error: redeclaration of 'max' with no linkage
     int L,M,max;
             ^
foo.c:5:17: note: previous definition of 'max' was here
   int i,b,c,j=0,max=0;
                 ^
foo.c:20:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^