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Cod sursa(job #141257)
#include<fstream.h>
#include<math.h>
long n;
long double s;
ifstream f("fractii.in");
ofstream g("fractii.out");
int prim(long a,long b)
{if(b%a==0) return 0;
if(b%2==0 && a%2==0) return 0;
if(b%3==0 && a%3==0) return 0;
if(b%5==0 && a%5==0) return 0;
if(b%7==0 && a%7==0) return 0;
if(b%11==0 && a%11==0) return 0;
while(a!=b)
if(a>b) a-=b;
else b-=a;
if(a==1) return 1;
else return 0;
}
int main()
{//int p;
f>>n;
s=2*n-1;
for (long i=2;i<n;i++)
for(long j=i+1;j<=n;j++)
if (prim(i,j)) s+=2;
g<<s;
f.close();
g.close();
return 0;
}