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input/code.cpp: In function 'int main()':
input/code.cpp:13:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
input/code.cpp:15:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&a[i]);
   ~~~~~^~~~~~~~~~~~

#include<bits/stdc++.h>
#define sz(x) ((int)(x).size())
#define all(x) x.begin(),x.end()
using namespace std;
using pi = pair<int,int>;
using lint = long long;
const int MAXN = 25; // 1000005;

int a[MAXN], b[MAXN], s[MAXN], g[MAXN];

int main(){
	int n;
	scanf("%d",&n);
	for(int i=0; i<n; ++i){
		scanf("%d",&a[i]);
		s[a[i]]++;
	}
	for(int i=2; i<MAXN; ++i){
		if(b[i] > 0) continue;
		b[i] = 1;
		for(int j=i+i; j<MAXN; j+=i) b[j] = b[j / i] + 1;
	}
	for(int i=2; i<MAXN; ++i){
		if(b[i] > 1) continue;
		lint c = 0;
		for(int j=i; j<MAXN; j+=i) c += s[j];
		for(int j=i; j<MAXN; j+=i) {
			g[j] += c * (b[i] & 1 ? 1 : -1);
		}
	}
	lint ans = 0;
	for(int i=0; i<n; ++i){
		ans += g[a[i]] - 1;
	}
	printf("%lld\n", lint(n) * (n - 1) / 2 - ans / 2);
}

Test 1

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 2

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 3

Group: 2, 3

Verdict: RUNTIME ERROR

Test 4

Group: 3

Verdict: RUNTIME ERROR

Test 5

Group: 3

Verdict: RUNTIME ERROR

Test 6

Group: 3

Verdict: RUNTIME ERROR

Test 7

Group: 3

Verdict: RUNTIME ERROR