foo.c: In function 'main':
foo.c:25:23: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if (ans==num||ans==10&&ch[len]=='X') printf("Right");
                ~~~~~~~^~~~~~~~~~~~~~
foo.c:9:5: warning: 'sum' is used uninitialized in this function [-Wuninitialized]
  sum+=num*1;
  ~~~^~~~~~~