1、

#include <stdio.h>
#include <ctype.h> 
#include <stdbool.h>

int main(void)
{
    char ch;
    bool word = false;
    bool space = false;
    int words = 0;
    
    while((ch = getchar()) != EOF)
    {
        if(!isspace(ch))
            word = true;
        if(isspace(ch))
            space = true;
        if(word && space)
        {
            words++;
            word = false;
            space = false;
        }
    }
    
    printf("words: %d.\n", words);
    
    return 0;
}