Cod sursa(job #392230)
#include <cstdio>
int phi(int n)
{
int rez=n,n2=n;
for(int i=2;i*i<=n2;i++)
if(n%i==0)
{
while(n%i==0)
n=n/i;
rez=rez/i*(i-1);
}
if(n>1)
return rez/n*(n-1);
return rez;
}
int ridicare(int a,int put,int n)
{
int rez=1;
while(put)
{
if(put%2==1)
rez=(rez*a)%n;
a=(a*a)%n;
put>>=1;
}
return rez;
}
int main()
{
int a,n,x;
int put;
freopen("inversmodular.in","r",stdin);
freopen("inversmodular.out","w",stdout);
scanf("%d%d",&a,&n);
put=phi(n)-1;
x=ridicare(a,put,n);
printf("%d",x);
return 0;
}