Language: C++

#define onlycc ios_base::sync_with_stdio(0);cin.tie(NULL);cout.tie(NULL)
#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <bits/stdc++.h>
#define MOD 1000000007
using namespace std;

typedef long long ll;
typedef int64_t ll;

#define EL printf("\n")
#define pb push_back
#define FOR(i,l,r) for (int i=l;i<=r;i++)
#define FORD(i,r,l) for (int i=r;i>=l;i--)

const int base = 1e9;
typedef vector<int> BigInt;

void Set(BigInt &a) {
    while (a.size() > 1 && a.back() == 0) a.pop_back();
}

void Print(BigInt a) {
    Set(a);
    printf("%d", (a.size() == 0) ? 0 : a.back());
    FORD(i,a.size()-2,0) printf("%09d", a[i]); EL;
}

BigInt Integer(string s) {
    BigInt ans;
    if (s[0] == '-') return ans;
    if (s.size() == 0) {ans.pb(0); return ans;}
    while (s.size()%9 != 0) s = '0'+s;
    for (int i=0;i<s.size();i+=9) {
        int v = 0;
        for (int j=i;j<i+9;j++) v = v*10+(s[j]-'0');
        ans.insert(ans.begin(),v);
    }
    Set(ans);
    return ans;
}

BigInt Integer(char c[]) {
    string s = "";
    FOR(i,0,strlen(c)-1) s = s + c[i];
    return Integer(s);
}

BigInt Integer(ll x) {
    string s = "";
    while (x > 0) s = char(x%10+'0') + s, x /= 10;
    return Integer(s);
}

BigInt Integer(int x) {
    return Integer((ll) x);
}

void operator >> (istream &in, BigInt &a) {
    string s;
    getline(cin, s);
    a = Integer(s);
}

void operator << (ostream &out, BigInt a) {
    Print(a);
}

bool operator < (BigInt a, BigInt b) {
    Set(a);
    Set(b);
    if (a.size() != b.size()) return (a.size() < b.size());
    FORD(i,a.size()-1,0)
        if (a[i] != b[i]) return (a[i] < b[i]);
    return false;
}

bool operator > (BigInt a, BigInt b) {
    return (b < a);
}

bool operator == (BigInt a, BigInt b) {
    return (!(a < b) && !(b < a));
}

bool operator <= (BigInt a, BigInt b) {
    return (a < b || a == b);
}

bool operator >= (BigInt a, BigInt b) {
    return (b < a || b == a);
}

bool operator < (BigInt a, int b) {
    return (a < Integer(b));
}

bool operator > (BigInt a, int b) {
    return (a > Integer(b));
}

bool operator == (BigInt a, int b) {
    return (a == Integer(b));
}

bool operator >= (BigInt a, int b) {
    return (a >= Integer(b));
}

bool operator <= (BigInt a, int b) {
    return (a <= Integer(b));
}

BigInt max(BigInt a, BigInt b) {
    if (a > b) return a;
    return b;
}

BigInt min(BigInt a, BigInt b) {
    if (a < b) return a;
    return b;
}

BigInt operator + (BigInt a, BigInt b) {
    Set(a);
    Set(b);
    BigInt ans;
    int carry = 0;
    FOR(i,0,max(a.size(), b.size())-1) {
        if (i < a.size()) carry += a[i];
        if (i < b.size()) carry += b[i];
        ans.pb(carry%base);
        carry /= base;
    }
    if (carry) ans.pb(carry);
    Set(ans);
    return ans;
}

BigInt operator + (BigInt a, int b) {
    return a + Integer(b);
}

BigInt operator ++ (BigInt &a) { // ++a
    a = a + 1;
    return a;
}

void operator += (BigInt &a, BigInt b) {
    a = a + b;
}

void operator += (BigInt &a, int b) {
    a = a + b;
}

BigInt operator &mdash; (BigInt a, BigInt b) {
    Set(a);
    Set(b);
    BigInt ans;
    int carry = 0;
    FOR(i,0,a.size()-1) {
        carry += a[i] &mdash; (i < b.size() ? b[i] : 0);
        if (carry < 0) ans.pb(carry+base), carry = -1;
        else ans.pb(carry), carry = 0;
    }
    Set(ans);
    return ans;
}

BigInt operator &mdash; (BigInt a, int b) {
    return a &mdash; Integer(b);
}

void operator -- (BigInt &a) { // --a
    a = a &mdash; 1;
}

void operator -= (BigInt &a, BigInt b) {
    a = a + b;
}

void operator -= (BigInt &a, int b) {
    a = a &mdash; b;
}

BigInt operator * (BigInt a, BigInt b) {
    Set(a);
    Set(b);
    BigInt ans;
    ans.assign(a.size()+b.size(), 0);
    FOR(i,0,a.size()-1) {
        ll carry = 0ll;
        for (int j=0;j<b.size() || carry > 0;j++) {
            ll s = ans[i+j] + carry + (ll)a[i]*(j<b.size()?(ll)b[j]:0ll);
            ans[i+j] = s%base;
            carry = s/base;
        }
    }
    Set(ans);
    return ans;
}

BigInt operator * (BigInt a, int b) {
    return a * Integer(b);
}

void operator *= (BigInt &a, BigInt b) {
    a = a * b;
}

void operator *= (BigInt &a, int b) {
    a = a * b;
}



BigInt operator / (BigInt a, BigInt b) {
    Set(a);
    Set(b);
    if (b == Integer(0)) return Integer("-1");
    BigInt ans, cur;
    FORD(i,a.size()-1,0) {
        cur.insert(cur.begin(), a[i]);
        int x = 0, L = 0, R = base;
        while (L <= R) {
            int mid = (L+R)>>1;
            if (b*Integer(mid) > cur) {
                x = mid;
                R = mid-1;
            }
            else
                L = mid+1;
        }
        cur = cur &mdash; Integer(x-1)*b;
        ans.insert(ans.begin(),x-1);
    }
    Set(ans);
    return ans;
}

BigInt operator / (BigInt a, int b) {
    Set(a);
    BigInt ans;
    ll cur = 0ll;
    FORD(i,a.size()-1,0) {
        cur = (cur*(ll)base + (ll)a[i]);
        ans.insert(ans.begin(),cur/b);
        cur %= b;
    }
    Set(ans);
    return ans;
}

void operator /= (BigInt &a, BigInt b) {
    a = a / b;
}

void operator /= (BigInt &a, int b) {
    a = a / b;
}

BigInt operator % (BigInt a, BigInt b) {
    Set(a);
    Set(b);
    if (b == Integer(0)) return Integer("-1");
    BigInt ans;
    FORD(i,a.size()-1,0) {
        ans.insert(ans.begin(), a[i]);
        int x = 0, L = 0, R = base;
        while (L <= R) {
            int mid = (L+R)>>1;
            if (b*Integer(mid) > ans) {
                x = mid;
                R = mid-1;
            }
            else
                L = mid+1;
        }
        ans = ans &mdash; Integer(x-1)*b;
    }
    Set(ans);
    return ans;
}

int operator % (BigInt a, int b) {
    Set(a);
    if (b == 0) return -1;
    int ans = 0;
    FORD(i,a.size()-1,0)
        ans = (ans*(base%b) + a[i]%b)%b;
    return ans;
}

void operator %= (BigInt &a, BigInt b) {
    a = a % b;
}

void operator %= (BigInt &a, int b) {
    a = a % Integer(b);
}

BigInt gcd(BigInt a, BigInt b) {
    Set(a);
    Set(b);
    while (b > Integer(0)) {
        BigInt r = a%b;
        a = b;
        b = r;
    }
    Set(a);
    return a;
}

BigInt lcm(BigInt a, BigInt b) {
    return (a*b/gcd(a,b));
}


BigInt sqrt(BigInt a) {
    BigInt x0 = a, x1 = (a+1)/2;
    while (x1 < x0) {
        x0 = x1;
        x1 = (x1+a/x1)/2;
    }
    return x0;
}

BigInt pow(BigInt a, BigInt b) {
    if (b == Integer(0)) return Integer(1);
    BigInt tmp = pow(a, b/2);
    if (b%2 == 0) return tmp * tmp;
    return tmp * tmp * a;
}

BigInt pow(BigInt a, int b) {
    return pow(a,(Integer(b)));
}

int log(int n, BigInt a) { // log_n(a)
    Set(a);
    int ans = 0;
    while (a > Integer(1)) {
        ans++;
        a /= n;
    }
    return ans;
}

ll ipow(int a, int b, int c)
{
    if(b == 0) return 1;

    long long ans = ipow(a, b/2, c);
    ans *= ans;
    ans %= c;

    if(b%2 == 1) (ans *= a) %= c;

    return ans;
}

int n;

int main()
{
    onlycc;
    cin >> n;

    BigInt ret1 = n*(n-1) % MOD;

    BigInt ret2 = ipow(10, n-2, MOD);

    BigInt ret = ret1*ret2%MOD;

    cout << ret;

    return 0;
}


Compiler output:
a.cc:11:17: error: conflicting declaration 'typedef int64_t ll'
   11 | typedef int64_t ll;
      |                 ^~
a.cc:10:19: note: previous declaration as 'typedef long long int ll'
   10 | typedef long long ll;
      |                   ^~
a.cc:159:18: error: expected initializer before 'mdash'
  159 | BigInt operator &mdash; (BigInt a, BigInt b) {
      |                  ^~~~~
a.cc:159:32: error: expected ')' before 'a'
  159 | BigInt operator &mdash; (BigInt a, BigInt b) {
      |                         ~      ^~
      |                                )
a.cc:173:18: error: expected initializer before 'mdash'
  173 | BigInt operator &mdash; (BigInt a, int b) {
      |                  ^~~~~
a.cc:173:32: error: expected ')' before 'a'
  173 | BigInt operator &mdash; (BigInt a, int b) {
      |                         ~      ^~
      |                                )
a.cc: In function 'void operator--(BigInt&)':
a.cc:178:12: error: 'mdash' was not declared in this scope
  178 |     a = a &mdash; 1;
      |            ^~~~~
a.cc: In function 'void operator-=(BigInt&, int)':
a.cc:186:12: error: 'mdash' was not declared in this scope
  186 |     a = a &mdash; b;
      |            ^~~~~
a.cc: In function 'BigInt operator/(BigInt, BigInt)':
a.cc:223:41: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
  223 |     if (b == Integer(0)) return Integer("-1");
      |                                         ^~~~
a.cc:237:20: error: 'mdash' was not declared in this scope
  237 |         cur = cur &mdash; Integer(x-1)*b;
      |                    ^~~~~
a.cc: In function 'BigInt operator%(BigInt, BigInt)':
a.cc:268:41: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
  268 |     if (b == Integer(0)) return Integer("-1");
      |                                         ^~~~
a.cc:282:20: error: 'mdash' was not declared in this scope
  282 |         ans = ans &mdash; Integer(x-1)*b;
      |                    ^~~~~
a.cc: In function 'int main()':
a.cc:372:27: error: conversion from 'int' to non-scalar type 'BigInt' {aka 'std::vector<int>'} requested
  372 |     BigInt ret1 = n*(n-1) % MOD;
      |                           ^
a.cc:374:23: error: conversion from 'll' {aka 'long long int'} to non-scalar type 'BigInt' {aka 'std::vector<int>'} requested
  374 |     BigInt ret2 = ipow(10, n-2, MOD);
      |                   ~~~~^~~~~~~~~~~~~~
a.cc:376:27: error: conversion from 'int' to non-scalar type 'BigInt' {aka 'std::vector<int>'} requested
  376 |     BigInt ret = ret1*ret2%MOD;
      |                           ^