/in/foo.c: In function 'main':
/in/foo.c:6:2: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
  scanf("%s %s",&a,&b);
  ^~~~~
/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:6:10: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'char (*)[101]' [-Wformat=]
  scanf("%s %s",&a,&b);
          ^
/in/foo.c:6:13: warning: format '%s' expects argument of type 'char *', but argument 3 has type 'char (*)[101]' [-Wformat=]
  scanf("%s %s",&a,&b);
             ^
/in/foo.c:7:6: warning: implicit declaration of function 'strlen' [-Wimplicit-function-declaration]
  len=strlen(a);
      ^~~~~~
/in/foo.c:7:6: warning: incompatible implicit declaration of built-in function 'strlen'
/in/foo.c:7:6: note: include '<string.h>' or provide a declaration of 'strlen'
/in/foo.c:16:3: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
   printf("Even\n");
   ^~~~~~
/in/foo.c:16:3: warning: incompatible implicit declaration of built-in function 'printf'
/in/foo.c:16:3: note: include '<stdio.h>' or provide a declaration of 'printf'
/in/foo.c:19:3: warning: incompatible implicit declaration of built-in function 'printf'
   printf("Odd\n");
   ^~~~~~
/in/foo.c:19:3: note: include '<stdio.h>' or provide a declaration of 'printf'
/in/foo.c:4:8: warning: unused variable 'j' [-Wunused-variable]
  int i,j,len;
        ^