#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define MAX_LEN 256
#define SPC " \t\n"
#define CHARS_NEEDED 4
int main(void){
char buf[MAX_LEN], *p;
size_t cnt;
printf("String: ");
if ( ! fgets(buf, MAX_LEN, stdin) ){
perror("fgets");
exit(1);
}
cnt = 0;
for ( p = strtok(buf, SPC); p; p = strtok(NULL, SPC) )
if ( strlen(p) == CHARS_NEEDED )
++cnt;
printf("%d words with length of %d characters\n", cnt, CHARS_NEEDED);
exit(0);
}