/in/foo.cc: In function 'int main()':
/in/foo.cc:5:26: warning: unused variable 'sum' [-Wunused-variable]
  long long s=1,i,j,n,m,x,sum=0;
                          ^~~
/in/foo.cc:26:11: warning: 'x' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<a[x]<<endl;
           ^