#include <iostream>
#include <fstream>
using namespace std;
ifstream in("euro.in");
ofstream out("euro.out");
int main(){
	int T, K, A[100],L,E;
	L = 0; E = 0;
		in >> K >> T;
		for (int i = 1; i <= K; i++)
			in >> A[i];
		for (int i = 1; i < K; i++) {
			E += A[i];
			if (L + E*i - T + A[i + 1] * (i + 1) - T >= L + (E + A[i + 1])*(i + 1) - T) {
				L += E*i - T;
				E = 0;
			}
		}
		L += (E+A[K])*K- T;

		out << L;
return 0;
}