#include <iostream> #include <iterator> #include <bits/stdc++.h> using namespace std; struct bign { int nums[3001]; int lens; bign() { memset(nums, 0, sizeof(nums)); lens = 0; } }; bign multiply(bign a, bign b) { bign res; int length; for (int i = 0; i < a.lens; i++) { int carry...