时间限制：C/C++/Rust/Pascal 2秒，其他语言4秒
空间限制：C/C++/Rust/Pascal 512 M，其他语言1024 M
64bit IO Format: %lld
空间限制：C/C++/Rust/Pascal 512 M，其他语言1024 M
64bit IO Format: %lld
题目描述
You are given four positive integers 𝑥, 𝑦, 𝑧, 𝑘, please help little M calculate the number of equations 𝑥 + 𝑦 + 𝑧 = 𝑘 when 0 ≤ 𝑥 ≤ 𝑎, 0 ≤ 𝑦 ≤ 𝑏, 0 ≤ 𝑧 ≤ 𝑐, 0 ≤ 𝑘 ≤ 𝑑
输入描述:
Four integers 𝑎, 𝑏, 𝑐, 𝑑 (0 ≤ 𝑎, 𝑏, 𝑐, 𝑑 ≤)
输出描述:
One integer the number of equations.It is guaranteed that all the answers fit 64-bit integer.