bool f (const char *s){int s1,s2,s3,s4;if (sscanf(s, "%d.%d.%d.%d", &s1, &s2, &s3, &s4) != 4){return false;}if ((s1 & 0xffffff00) || (s2 & 0xffffff00) || (s3 & 0xffffff00) || (s4 & 0xffffff00)){return false;}else{return true;}}