View Compilation Error

0_0_36880318_27465.cpp: In function 'void solve()':
0_0_36880318_27465.cpp:53:3: error: 'sum' was not declared in this scope
   sum += a[i];
   ^
0_0_36880318_27465.cpp:98:6: error: 'flag' was not declared in this scope
   if(flag) x = -x;
      ^