Search word from sentence

/* Search a word ( example : book ) from a sentence and show nth number where the word is in the sentence */

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

int main(void)
{
    char str[80];
    gets(str);
    int length=strlen(str);
    int i;
    int counter=1;
    for(i=0;i<length;i++)
    {
        if(str[i]==' ')
        {
            counter++;
        }

        if(str[i]=='b'&&str[i+1]=='o'&&str[i+2]=='o'&&str[i+3]=='k')
        {
            printf("found\n");
            printf("%d \n",counter);
            return 0;
        }
    }
    if(counter==0)
    {
        printf("not found \n");
    }
   return 0;
}