#include<stdio.h>
#include<stdlib.h>
 
int main(void) {
  char s[64], *w;
  int sheep, wolf, i = 0;
  
  scanf("%[^\n]", 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;
}