The sum of elements of a two-dimensional array

Given a two-dimensional array of size $n\times m$. Find the sum of its elements.

Input

The first line of the input contains two numbers $n$ and $m$, the number of rows and the number of columns, respectively.

The following $n$ lines each contain $m$ numbers - the elements of the array.

Output

Output a single number, the sum of the elements of the array.

Examples