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

int main(int argc, char **argv) {
char *s, line[256], lastline[256];

  *lastline = '\0';
  for (;;) {
    if (gets(line) == NULL) break;
    s = strchr(line, '\n'); if (s != NULL) *s = '\0';

    if ((*lastline) && (strncmp(line, lastline, strlen(lastline)) == 0)) {
      printf("%s =< %s\n", line, lastline);
    }
    strcpy(lastline, line);
  }
  return(0);
}