#include int isalpha(int c) { return islower(c) || isupper(c); } int isalnum(int c) { return isalpha(c) || isdigit(c); } int isdigit(int c) { return '0' <= c && c <= '9'; } int islower(int c) { return 'a' <= c && c <= 'z'; } int isspace(int c) { return c == ' ' || c == '\f' || c == '\n' || c == '\r' || c == '\t' || c == '\v'; } int isupper(int c) { return 'A' <= c && c <= 'Z'; }