Count Articles of a string without Library function.

#include<stdio.h>
int cnt;
char str[10000];
void count_article(char *article,int string_len)
{
    int i,j,f,article_len;
    article_len=strlen(article);
    for(i=0;i<string_len;i++){
        f=1;
        for(j=0;j<article_len;j++){
            if(f==1){
                if(i+j>=string_len||article[j]!=str[i+j]){
                    f=0;
                }
            }
        }
        if(f==1){
            cnt++;
        }
    }
}
int main()
{
    int len;
    scanf("%[^\n]s",str);
    len=strlen(str);
    cnt=0;
    count_article("A ",len);
    count_article(" a ",len);
    count_article("An ",len);
    count_article(" an ",len);
    count_article("The ",len);
    count_article(" the ",len);
    printf("%d\n",cnt);
    return 0;
}