Sum of subarray elements

Input

The first line contains two integers, $n$ and $m (1 \leq n, m \leq 100)$ m~(1 \le n, m \le 100), representing the number of rows and columns, respectively.

The next $n$ lines each contain $m$ integers representing the elements of the array. The absolute value of each array element does not exceed $100$ .

The last line contains four integers: $r_{1}, c_{1}, r_{2}$ r_1, c_1, r_2, and $c_{2} (r_{1} \leq r_{2}, c_{1} \leq c_{2})$ c_2~(r_1 \le r_2, c_1 \le c_2). These values specify the row and column indices of the top-left and bottom-right corners of the subarray, respectively.

The array is $1$ -indexed, meaning that its rows and columns are numbered starting from $1$ .

Output

Print the sum of all elements in the specified subarray.

Examples

Example 1

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