Count the number of words C language

subject ： Enter a line of characters , Statistics of which English words The number of . Space between words .

#define N 50

int main(void){
    char str[N];
    printf(" Please enter ：");
	gets(str);
	char *p;
	p = str;
	int sum=0;
    while(*p){
        if(*p>='a'&&*p<='z' || *p>='A'&&*p<='Z'){
            sum++;
        }
        p++;
    }
    printf(" Altogether %d Word ！",sum);
    return 0;
}

subject ： Enter a line of characters , Statistics of which word The number of . Space between words . 

#define N 50
 
int main(void){
    char str[N];
    printf(" Please enter ：");
	gets(str);
	char *p;
	p = str;
	int sum=0,flag=0;
    while(*p){
        if(*p == ' '){
            flag = 0;
        }else if(flag == 0){
            sum++;
            flag = 1;
        }
        p++;
    }
    printf(" Altogether %d Word ！",sum);
    return 0;
}