View Compilation Error

0_0_36006285_17129.cpp:4:1: error: expected initializer before 'const'
 const ll mod=1e9+7;
 ^
0_0_36006285_17129.cpp:5:1: error: 'll' does not name a type
 ll ksm(ll n,ll m){
 ^
0_0_36006285_17129.cpp: In function 'int main()':
0_0_36006285_17129.cpp:17:5: error: 'll' was not declared in this scope
     ll n;
     ^
0_0_36006285_17129.cpp:18:26: error: 'n' was not declared in this scope
     while(~scanf("%dll",&n)){
                          ^
0_0_36006285_17129.cpp:19:12: error: expected ';' before 'a'
         ll a=n+(ll)1 ;
            ^
0_0_36006285_17129.cpp:20:15: error: 'a' was not declared in this scope
         cout<<a*ksm((ll)2*n,mod-2)%mod<<endl;
               ^
0_0_36006285_17129.cpp:20:25: error: expected ')' before numeric constant
         cout<<a*ksm((ll)2*n,mod-2)%mod<<endl;
                         ^
0_0_36006285_17129.cpp:20:29: error: 'mod' was not declared in this scope
         cout<<a*ksm((ll)2*n,mod-2)%mod<<endl;
                             ^
0_0_36006285_17129.cpp:20:34: error: 'ksm' was not declared in this scope
         cout<<a*ksm((ll)2*n,mod-2)%mod<<endl;
                                  ^