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Cod sursa(job #109242)
#include <cstdio>
const int maxn = 100001;
const int maxp = 2000;
FILE *in = fopen("pairs.in","r"), *out = fopen("pairs.out","w");
int n;
int a[maxn];
//int k;
//char x[maxp];
//int primes[maxp];
//void ciur()
//{
// primes[++k] = 2;
//
// for ( int i = 4; i <= maxp; i += 2 )
// x[i] = 'x';
//
// for ( int i = 3; i <= maxp; i += 2 )
// if ( x[i] != 'x' )
// {
// primes[++k] = i;
//
// for ( int j = i+i; j <= maxp; j += i )
// x[j] = 'x';
// }
//}
//int h[maxp]; // h[i] = cate numere au ca factor prim i
void read()
{
fscanf(in, "%d", &n);
for ( int i = 1; i <= n; ++i )
{
fscanf(in, "%d", &a[i]);
// for ( int j = 1; primes[j] <= a[i]; ++j )
// if ( a[i] % primes[j] == 0 )
// ++h[ primes[j] ];
}
}
int cmmdc(int a, int b)
{
if ( b == 0 )
return a;
return cmmdc(b, a % b);
}
int main()
{
// ciur();
read();
long long cnt = 0;
//
// int temp = 0;
//
// for ( int i = 1; i <= 20; ++i )
// printf("%d %d\n", i, h[i]);
// printf("\n");
for ( int i = 1; i <= n; ++i )
for ( int j = i+1; j <= n; ++j )
if ( cmmdc(a[i], a[j]) == 1 )
++cnt;
fprintf(out, "%lld\n", cnt);
return 0;
}