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

int main() {
	int arr[]= {2,0,1,3,-1};
	int n=sizeof(arr)/sizeof(arr[0]);
	int count=0;
	int currentSum=0;
	unordered_map<int, int> mp;
	mp[0]=1;
	for(int j=0;j<n;j++){
		currentSum = currentSum + arr[j];
		int rhs = currentSum-(j+1);
		if(mp.find(rhs)!=mp.end()){
			count = count + mp[rhs];
		}
		mp[rhs]++;
	}
	cout<<count;
	return 0;
}