编译失败!大神看过来

#include <stdio.h>
#include <string.h>
int main()
{
    char c,word[15],thisword[15],article[1000005];
    int i,j=0,flag=0,ans=0;
    gets(word);
    gets(article);
    strlwr(word);
    strlwr(article);
    strcat(article," ");
    for(i=0; i<strlen(article); i++)
    {
        c=article[i];
        if(c!=' ')
        {
            thisword[j++]=c;
            flag=1;
        }
        else if(flag)
        {
            thisword[j]='\0';
            if (!strcmp(word,thisword))ans++;
            flag=0;
            j=0;
        }
    }
    if(!ans)ans=-1;
    printf("%d",ans);
    return 0;
}