Problem:
Score : 100 points

Problem Statement

There are S sheep and W wolves.

If the number of wolves is greater than or equal to that of sheep, the wolves will attack the sheep.

If the wolves will attack the sheep, print unsafe; otherwise, print safe.

Constraints

1 \leq S \leq 100

1 \leq W \leq 100

Input

Input is given from Standard Input in the following format:

S W

Output

If the wolves will attack the sheep, print unsafe; otherwise, print safe.

Sample Input 1

4 5

Sample Output 1

unsafe

There are four sheep and five wolves. The number of wolves is not less than that of sheep, so they will attack them.

Sample Input 2

100 2

Sample Output 2

safe

Many a sheep drive away two wolves.

Sample Input 3

10 10

Sample Output 3

unsafe

Solution in C (GCC 9.2.1) (judge verdict: Wrong Answer)

#include<stdio.h>
#include<string.h>
#include<math.h>
#define N_MAX 200001
#define ll long long
#define MOD 2019



int main(){
  int g=1,len;
  ll ans=0;
  char a[N_MAX];
  scanf("%s",a);
  len=strlen(a);
  int T[len+1];
  T[len]=0;
  int counter[MOD]={};
  counter[0]=1;
  for(int k=len-1;k>=0;k--){
    T[k]=(T[k+1]+g*(a[k]-'0'))%MOD;
    counter[T[k]]++;
          g*10;
          g%2019;
  };
  for(int b=0;b<MOD;b++){
    ans+=counter[b]*(counter[b]-1)/2;
  };
  printf("%lld",ans);
};