/in/foo.c: In function 'main':
/in/foo.c:6:2: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
  scanf("%d%d",&x1,&n1);
  ^~~~~
/in/foo.c:6:2: warning: incompatible implicit declaration of built-in function 'scanf'
/in/foo.c:6:2: note: include '<stdio.h>' or provide a declaration of 'scanf'
/in/foo.c:34:3: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
   printf("%d", c[i]);
   ^~~~~~
/in/foo.c:34:3: warning: incompatible implicit declaration of built-in function 'printf'
/in/foo.c:34:3: note: include '<stdio.h>' or provide a declaration of 'printf'
/in/foo.c:4:39: warning: unused variable 'jw' [-Wunused-variable]
  int x1,n1,x2,n2,i,na=1,nb=1,nc=0,y=0,jw=0,j;
                                       ^~
/in/foo.c:4:35: warning: unused variable 'y' [-Wunused-variable]
  int x1,n1,x2,n2,i,na=1,nb=1,nc=0,y=0,jw=0,j;
                                   ^
/in/foo.c:4:30: warning: unused variable 'nc' [-Wunused-variable]
  int x1,n1,x2,n2,i,na=1,nb=1,nc=0,y=0,jw=0,j;
                              ^~