#include <stdio.h>

int main(int argc, const char* argv[])
{
	int sheepNum, wolfNum;
	scanf("%d %d", &sheepNum, &wolfNum);

	// If there are more(or equal) wolves than sheeps, program will print unsafe. In other case it will print safe.
	if (wolfNum >= sheepNum)
	{
		printf("unsafe");
	}
	else
	{
		printf("safe");
	}

	return 0;
}