#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 (s <= w) {
        printf("unsafe\n");
    }
    else {
        printf("safe\n");
    }
    return 0;
}