#include <stdio.h>

void main() {

    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 ", &s);
    }
    y = fgets(W, sizeof(W), stdin);
    if (y != NULL) {
       sscanf(W, "%d", &w);
    }
    if (s <= w) {
        printf("unsafe");
    }
    else {
        printf("safe");
    }
    return;
}