#include <stdio.h>
#include <string.h>

int isSheepSafe()
{
	int sheepNum, wolfNum;
	scanf("%d %d", &sheepNum, &wolfNum);

	if (wolfNum >= sheepNum)
	{
		return 0;
	}
	else
	{
		return 1;
	}
}

int main(int argc, const char* argv[])
{
	int sheepSafety = isSheepSafe();

	if (sheepSafety == 0)
	{
		printf("unsafe");
	}
	else
	{
		printf("safe");
	}

	return 0;
}