foo.cpp:1:1: error: 'include' does not name a type
 include <iostream>
 ^~~~~~~
foo.cpp:20:7: error: 'll' does not name a type
 const ll mod=1e9+7;
       ^~
foo.cpp:21:1: error: 'll' does not name a type
 ll fac[MAXN];
 ^~
foo.cpp:22:1: error: 'll' does not name a type
 ll quick_mod(ll a,ll b,ll m)
 ^~
foo.cpp: In function 'void init()':
foo.cpp:39:1: error: 'fac' was not declared in this scope
 fac[0]=1;
 ^~~
foo.cpp:40:17: error: 'MAXN' was not declared in this scope
 for (int i=1;i<=MAXN;i++)
                 ^~~~
foo.cpp:41:21: error: 'mod' was not declared in this scope
 fac[i]=fac[i-1]*i % mod;
                     ^~~
foo.cpp: At global scope:
foo.cpp:43:1: error: 'll' does not name a type
 ll C(ll a,ll b)
 ^~
foo.cpp: In function 'void solve()':
foo.cpp:49:1: error: 'll' was not declared in this scope
 ll x1,x2,y1,y2;
 ^~
foo.cpp:50:1: error: 'cin' was not declared in this scope
 cin>>x1>>x2>>y1>>y2;
 ^~~
foo.cpp:50:6: error: 'x1' was not declared in this scope
 cin>>x1>>x2>>y1>>y2;
      ^~
foo.cpp:50:10: error: 'x2' was not declared in this scope
 cin>>x1>>x2>>y1>>y2;
          ^~
foo.cpp:50:14: error: 'y1' was not declared in this scope
 cin>>x1>>x2>>y1>>y2;
              ^~
foo.cpp:50:18: error: 'y2' was not declared in this scope
 cin>>x1>>x2>>y1>>y2;
                  ^~
foo.cpp:52:4: error: expected ';' before 'ans'
 ll ans= C(x1+y1,x1) * C(x2+y2,x2) % mod - C(x1+y2,x1) * C(x2+y1,x2) % mod;
    ^~~
foo.cpp:53:1: error: 'ans' was not declared in this scope
 ans = ( ans + mod ) % mod;
 ^~~
foo.cpp:53:15: error: 'mod' was not declared in this scope
 ans = ( ans + mod ) % mod;
               ^~~
foo.cpp:54:1: error: 'cout' was not declared in this scope
 cout<<ans<<endl;
 ^~~~
foo.cpp:54:12: error: 'endl' was not declared in this scope
 cout<<ans<<endl;
            ^~~~