import java.util.$*$;

class DiagonalSumDebug $\{$

public static void main$($String args$[])\{$

Scanner sc $=$ new Scanner$($System$.$in$)$;

int n $=$ sc$.$nextInt$()$;

int m $=$ sc$.$nextInt$()$;

int x $=$ sc$.$nextInt$()$;

int y $=$ sc$.$nextInt$()$;

int a$[][]=$ new int$[100001][100001]$;

for $($int i $=0$; i $<$ n; i$++)\{$

for $($int j $=0$; j $<$ m; j$++)$

a$[$i$][$j$]=$ sc$.$nextInt$()$;

$\}$

int result $=$ diagonalSum$($a$,$x$,$y$,$n$,$m$)$;

System.out.println$($result$)$;

$\}$

static int diagonalSum$($int$[][]$ a$,$int n$,$int m$,$int i$,$int j$)\{$

if $($i $>=$ n $||$ j $>=$ m$)\{$

return $-1$;

$\}$

int diagonalSum;

int row $=$ i;

int col $=$ j;

while $($row $<$ n$)$

$\{$

diagonalSum $+=$ a$[$row$][$col$]$;

row$++$;

col$++$;

$\}$

return diagonalSum;

$\}$

$\}$ Problem Description

Given a matrix of dimensions n x m$,$ you are tasked with finding the sum of elements by starting at the index $($i$,$ j$)$ and moving in a diagonal order.

Write a function that takes the matrix, starting index $($i$,$ j$),$ and returns the sum of the elements encountered while moving diagonally. If the starting index is invalid, return $-1$

Input format

First line contains integers n and m$.$

Second line contains starting index i and j$.$

In next n lines each line contains m elements.

Output format

An integer representing the sum.

Sample Input $1$

$44$

$01$

$1234$

$1245$

$2334$

$1123$

Sample Output $1$

$10$

Explanation

Diagonal elements starting at index $(0,2)$ are $2,4,4.$

Their sum is $10.$

Constraints

$1<=$ n$,$m $<=100$

$0<=$ i$,$j $<100$

$0<=$ element of matrix $<=10^5$