#include <stdio.h>

int main(void) {

    int s, w;
    char S[100 + 1];
    char W[100 + 1];
    char *x;
    char *y;
    
        x = fgets(S, sizeof(W), stdin);
        if (x != NULL) {
          sscanf(S,"%d\n", &s);
        }
        y = fgets(W, sizeof(W), stdin);
        if (y != NULL) {
           sscanf(W, "%d\n", &w);
        }
        if ((1 <= s && s <=101) && (1 <= w && w <= 100)) {
            if (s <= w) {
               printf("unsafe\n");
            }
            else {
                printf("safe\n");
            }
         }
    return 0;
}