#include<iostream>
using namespace std;
int main(){
	long long n,k,T,m=1,sum=1;
	cin>>n>>k>>T;
	for(long long i=1;i<T;i++){
		m=(m+((i-1)*n+1+i*n)*n/2)%k;
		sum+=m;
	}
	cout<<sum;
	return 0;
}