Language: C++

#include <bits/stdc++.h>
#include <algorithm>
#define _GLIBCXX_DEBUG
#define rep(i,n) for(int i=0;i<(n);++i)
#define all(x) (x).begin(), (x).end()
#define PB(x) push_back(x)
#define MP(x,y) make_pair(x,y)
using namespace std;
typedef long long ll;

// auto mod int

const int mod = 1000000007;
struct mint {
  ll x; // typedef long long ll;
  mint(ll x=0):x((x%mod+mod)%mod){}
  mint operator-() const { return mint(-x);}
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += mod-a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const {
    mint res(*this);
    return res+=a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res-=a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res*=a;
  }
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t>>1);
    a *= a;
    if (t&1) a *= *this;
    return a;
  }

  // for prime mod
  mint inv() const {
    return pow(mod-2);
  }
  mint& operator/=(const mint a) {
    return (*this) *= a.inv();
  }
  mint operator/(const mint a) const {
    mint res(*this);
    return res/=a;
  }
};

ll mod_pow(ll x,ll n,ll mod){
  if(n==0)return 1;
  ll res=mod_pow(x*x%mod,n/2,mod);
  if(n&1)res=res*x%mod;
  return res;
}

mint choose(int n,int a) {
    mint x=1,y=1;
    rep(i,a) {
        x*=n-i;
        y*=i+1;
    }
    return x/y;
}

int main() {

    int n,a,b;
    cin >> n >> a >> b;

    mint ans=mint(2).pow(n);
    ans-=1;
    ans-=choose(n,a);
    ans-=choose(n,b);

    cout<<ans<<endl;

 
 return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:89:9: error: no match for 'operator<<' (operand types are 'std::ostream' {aka 'std::basic_ostream<char>'} and 'mint')
   89 |     cout<<ans<<endl;
      |     ~~~~^~~~~
      |     |     |
      |     |     mint
      |     std::ostream {aka std::basic_ostream<char>}
In file included from /usr/include/c++/14/istream:41,
                 from /usr/include/c++/14/sstream:40,
                 from /usr/include/c++/14/complex:45,
                 from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127,
                 from a.cc:1:
/usr/include/c++/14/ostream:116:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(__ostream_type& (*)(__ostream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  116 |       operator<<(__ostream_type& (*__pf)(__ostream_type&))
      |       ^~~~~~~~
/usr/include/c++/14/ostream:116:36: note:   no known conversion for argument 1 from 'mint' to 'std::basic_ostream<char>::__ostream_type& (*)(std::basic_ostream<char>::__ostream_type&)' {aka 'std::basic_ostream<char>& (*)(std::basic_ostream<char>&)'}
  116 |       operator<<(__ostream_type& (*__pf)(__ostream_type&))
      |                  ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/ostream:125:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(__ios_type& (*)(__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>; __ios_type = std::basic_ios<char>]'
  125 |       operator<<(__ios_type& (*__pf)(__ios_type&))
      |       ^~~~~~~~
/usr/include/c++/14/ostream:125:32: note:   no known conversion for argument 1 from 'mint' to 'std::basic_ostream<char>::__ios_type& (*)(std::basic_ostream<char>::__ios_type&)' {aka 'std::basic_ios<char>& (*)(std::basic_ios<char>&)'}
  125 |       operator<<(__ios_type& (*__pf)(__ios_type&))
      |                  ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
/usr/include/c++/14/ostream:135:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::ios_base& (*)(std::ios_base&)) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  135 |       operator<<(ios_base& (*__pf) (ios_base&))
      |       ^~~~~~~~
/usr/include/c++/14/ostream:135:30: note:   no known conversion for argument 1 from 'mint' to 'std::ios_base& (*)(std::ios_base&)'
  135 |       operator<<(ios_base& (*__pf) (ios_base&))
      |                  ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
/usr/include/c++/14/ostream:174:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  174 |       operator<<(long __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:174:23: note:   no known conversion for argument 1 from 'mint' to 'long int'
  174 |       operator<<(long __n)
      |                  ~~~~~^~~
/usr/include/c++/14/ostream:178:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  178 |       operator<<(unsigned long __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:178:32: note:   no known conversion for argument 1 from 'mint' to 'long unsigned int'
  178 |       operator<<(unsigned long __n)
      |                  ~~~~~~~~~~~~~~^~~
/usr/include/c++/14/ostream:182:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(bool) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  182 |       operator<<(bool __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:182:23: note:   no known conversion for argument 1 from 'mint' to 'bool'
  182 |       operator<<(bool __n)
      |                  ~~~~~^~~
In file included from /usr/include/c++/14/ostream:1022:
/usr/include/c++/14/bits/ostream.tcc:96:5: note: candidate: 'std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short int) [with _CharT = char; _Traits = std::char_traits<char>]'
   96 |     basic_ostream<_CharT, _Traits>::
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/ostream.tcc:97:22: note:   no known conversion for argument 1 from 'mint' to 'short int'
   97 |     operator<<(short __n)
      |                ~~~~~~^~~
/usr/include/c++/14/ostream:189:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(short unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  189 |       operator<<(unsigned short __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:189:33: note:   no known conversion for argument 1 from 'mint' to 'short unsigned int'
  189 |       operator<<(unsigned short __n)
      |                  ~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/ostream.tcc:110:5: note: candidate: 'std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(int) [with _CharT = char; _Traits = std::char_traits<char>]'
  110 |     basic_ostream<_CharT, _Traits>::
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/ostream.tcc:111:20: note:   no known conversion for argument 1 from 'mint' to 'int'
  111 |     operator<<(int __n)
      |                ~~~~^~~
/usr/include/c++/14/ostream:200:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  200 |       operator<<(unsigned int __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:200:31: note:   no known conversion for argument 1 from 'mint' to 'unsigned int'
  200 |       operator<<(unsigned int __n)
      |                  ~~~~~~~~~~~~~^~~
/usr/include/c++/14/ostream:211:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  211 |       operator<<(long long __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:211:28: note:   no known conversion for argument 1 from 'mint' to 'long long int'
  211 |       operator<<(long long __n)
      |                  ~~~~~~~~~~^~~
/usr/include/c++/14/ostream:215:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  215 |       operator<<(unsigned long long __n)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:215:37: note:   no known conversion for argument 1 from 'mint' to 'long long unsigned int'
  215 |       operator<<(unsigned long long __n)
      |                  ~~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/ostream:231:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(double) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  231 |       operator<<(double __f)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:231:25: note:   no known conversion for argument 1 from 'mint' to 'double'
  231 |       operator<<(double __f)
      |                  ~~~~~~~^~~
/usr/include/c++/14/ostream:235:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(float) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  235 |       operator<<(float __f)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:235:24: note:   no known conversion for argument 1 from 'mint' to 'float'
  235 |       operator<<(float __f)
      |                  ~~~~~~^~~
/usr/include/c++/14/ostream:243:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long double) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  243 |       operator<<(long double __f)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:243:30: note:   no known conversion for argument 1 from 'mint' to 'long double'
  243 |       operator<<(long double __f)
      |                  ~~~~~~~~~~~~^~~
/usr/include/c++/14/ostream:301:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(const void*) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>]'
  301 |       operator<<(const void* __p)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:301:30: note:   no known conversion for argument 1 from 'mint' to 'const void*'
  301 |       operator<<(const void* __p)
      |                  ~~~~~~~~~~~~^~~
/usr/include/c++/14/ostream:306:7: note: candidate: 'std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::nullptr_t) [with _CharT = char; _Traits = std::char_traits<char>; __ostream_type = std::basic_ostream<char>; std::nullptr_t = std::nullptr_t]'
  306 |       operator<<(nullptr_t)
      |       ^~~~~~~~
/usr/include/c++/14/ostream:306:18: note:   no known conversion for argument 1 from 'mint' to 'std::nullptr_t'
  306 |       operator<<(nullptr_t)
      |                  ^~~~~~~~~
/usr/include/c++/14/bits/ostream.tcc:124:5: note: candidate: 'std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(__streambuf_type*) [with _CharT = char; _Traits = std::char_traits<char>; __st