__in128 template

i128.cpp

#include <bits/stdc++.h>
#define ll long long
#define FASTIO   \
  cin.tie(NULL); \
  ios::sync_with_stdio(false);
#define END return 0;
#define out cout <<
#define in cin >>
#define i128 __int128
using namespace std;
ostream& operator<<(ostream& os, i128 x) {
    if(x == 0) {
        os << '0';
        return os;
    }
    if(x < 0) {
        os << '-';
        x = -x;
    }
    string s;
    while(x > 0) {
        s.push_back('0' + x % 10);
        x /= 10;
    }
    reverse(s.begin(), s.end());
    os << s;
    return os;
}