#include<stdio.h>
#include<stdlib.h>
 
int main(void) {
  char *s, *w;
  int sheep, wolf, i = 0;
  
  scanf("%s", s);
  
  while (s[i++] == ' ');
  
  s[--i] == '\0';
  w = &s[++i];
  
  sheep = atoi(s);
  wolf = atoi(w);
  
  if (sheep > wolf) {
    printf("safe");
  } else {
    printf("unsafe");
  }
  
  return 0;
}
  
  
#include<stdio.h>
#include<stdlib.h>

int main(void) {
  char *s, *w;
  int sheep, wolf, i = 0;
  
  scanf("%s", s);
  
  while (s[i++] == '');
  
  s[--i] == '\0';
  w = &s[++i];
  
  sheep = atoi(s);
  wolf = atoi(w);
  
  if (sheep > wolf) {
    printf("safe");
  } else {
    printf("unsafe");
  }
  
  return 0;
}