/**

author:	©LoneWolfDON
Git: MahinHossainMunna

**/
/*

*/

#include <stdio.h>

int main()
{
    int S, W;

    scanf("%d%d", &S, &W);

    if(W >= S)
        printf("unsafe\n");
    else
        printf("safe\n");

    return 0;
}
