#include <iostream>

using namespace std;

class Q{
private:
	int a[100];
	int n;
	int k, l;
public:
	void Enter(){
		cout << "Vvedite dlinu massiva" << endl;
		cin >> n;
		cout << "Vvedite elementi massiva" << endl;
		for (int q=0; q<n; q++)
			cin >> a[q];
		cout << "Vvedite chislo k" << endl;
		cin >> k;
		cout << "Vvedite chislo l" << endl;
		cin >> l;
	}
	void Output(){
		cout << endl;
		for (int q=0; q<n; q++)
			cout << a[q] << " ";
		cout << endl;
	}
	void TaskOutPut(){
		int sum = 0;
		for (int q=k-1; q<=l-1; q++)
			sum += a[q];
		cout << sum << endl;			
	}

};

int main(){
	Q obj;
	obj.Enter();
	obj.TaskOutPut();
}