Sum of Counts

For integers $a, b, c \ge 0$, let $f(a, b, c)$ be the number of integer ordered pairs $(x, y)$ that satisfy $0 \le x \le a$, $0 \le y \le b$, and $x + y = c$.

For example, the integer ordered pairs $(x, y)$ satisfying $0 \le x \le 2$, $0 \le y \le 3$, and $x + y = 3$ are $(0, 3), (1, 2), (2, 1)$, three in total. So $f(2, 3, 3) = 3$.

Given positive integers $n, m$, find

$\sum_{i=0}^{n+m} f(n, m, i) = f(n, m, 0) + f(n, m, 1) + \cdots + f(n, m, n+m)$

For example, when $n = 2, m = 1$, we have $f(2, 1, 0) = 1, f(2, 1, 1) = 2, f(2, 1, 2) = 2, f(2, 1, 3) = 1$. Therefore the answer is $1 + 2 + 2 + 1 = 6$.

The first line contains positive integers $n, m$ separated by a space. ($1 \le n, m \le 100$)

Print the answer to the problem on the first line.