public class Solution {
    public int NumberOfArithmeticSlices(int[] A) {
        int curr = 0, sum = 0;
            for (int i = 2; i < A.Length; i++)
                if (A[i] - A[i - 1] == A[i - 1] - A[i - 2])
                {
                    curr += 1;
                    sum += curr;
                }
                else
                {
                    curr = 0;
                }
            return sum;
    }
}