View Compilation Error

0_0_17625793_19022.cpp:64:10: error: '::main' must return 'int'
 int main()
          ^
0_0_17625793_19022.cpp: In function 'int main()':
0_0_17625793_19022.cpp:83:9: error: 'LL' was not declared in this scope
         LL ans=0,sum=0;
         ^
0_0_17625793_19022.cpp:86:35: error: incompatible types in assignment of 'long long int' to 'long long int [100050]'
         for (int i=1;i<=n;i++) sum+=dis[i];
                                   ^
0_0_17625793_19022.cpp:101:13: error: 'ans' was not declared in this scope
             ans+=(LL)(n-mem[i])*(LL)(mem[i])*(LL)dis[i];
             ^
0_0_17625793_19022.cpp:104:13: error: 'ans' was not declared in this scope
         dd=(ans+0.0)*2/n/(n-1);
             ^