#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 5;
struct bigint{
	int len, a[N];
	friend bigint operator + (bigint a, bigint b){
		bigint c;
		c.len = max(a.len, b.len);
		for(int i = 1; i <= c.len; i++)
			c.a[i] = a.a[i] + b.a[i];
		for(int i = 1; i <= c.len; i++)
			c.a[i + 1] += c.a[i] / 10, c.a[i] %= 10;
		while(c.a[c.len + 1]) c.len++;
		return c;
	}
};
int n;
int main(){
	cin >> n;
	bigint A, B, C;
	C = A + B;
	return 0;
}

为什么这代码一运行（也就是说，黑框一弹出），就停止工作了（不用管代码的用途）。

返回值 3221225725