Codeforces 986B - Petr and Permutations

$\text{Description}$

$\text{Given an array }a[],\text{ swap random 2 number of them for }3n\text{ or }(7n+1)\text{ times.}$
$\text{Please compute how many times for swaping.}$

$\text{Solution}$

$\text{It's easy to know that if we keep swaping }a[i]\text{ and }a[a[i]],\text{ they'll always}$
$\text{goes }a[i]=i\text{ at last.}$
$\text{Counting times we've done that so that }\forall i,a[i]=i.\text{ Check its parity.}$

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>

int n;
int a[1000010];
int ans=0;

int main(){
	scanf("%d",&n);
	for(int i=1;i<=n;++i)
		scanf("%d",&a[i]);
	for(int i=1;i<=n;++i)
		while(a[i]!=i){
			std::swap(a[i],a[a[i]]);
			++ans;
		}
	if(ans%2==n%2) puts("Petr");
	else puts("Um_nik");
}