Ruby program to calculate the sum of matrix elements

TwoDArr = Array.new(2){Array.new(2)}
sum = 0;

printf "Enter elements of MATRIX:\n";
i = 0;
while (i < 2) 
  j = 0;
  while (j < 2) 
    printf "ELEMENT [%d][%d]: ", i, j;
    TwoDArr[i][j] =  gets.chomp.to_i;
    j = j + 1;
  end
  i = i + 1;
end

printf "MATRIX:\n";
i = 0;
while (i < 2)
  j = 0;
  while (j < 2) 
    sum = sum +TwoDArr[i][j];
    print TwoDArr[i][j]," ";
    j = j + 1;
  end
  i = i + 1;
  print "\n";
end

printf "Sum of matrix elements: %d\n",sum;

Output:

Enter elements of MATRIX:
ELEMENT [0][0]: 1
ELEMENT [0][1]: 2
ELEMENT [1][0]: 3
ELEMENT [1][1]: 4
MATRIX:
1 2 
3 4
Sum of matrix elements: 10