#include <bits/stdc++.h>
using namespace std;

int main() {
	int n;
	cin>>n;
	
	vector<int> numbers(n);
	
	for(auto& number: numbers){
		cin>>number;
	}
	
	int answer = 0;
	
	unordered_map<int,int> prefixSum;
	
	prefixSum[0] = 1;
	
	int sum = 0;
	
	for(int i=0; i<n; i++){
		sum += numbers[i];
		
		
		if(prefixSum.find(sum - i - 1) != prefixSum.end()){
			answer+=prefixSum[sum-i-1];
		}
		
		prefixSum[sum-i-1]++;
	}
	
	cout << answer;
	
	return 0;
}