View Compilation Error

0_0_39156291_24118.cpp: In function 'void solve()':
0_0_39156291_24118.cpp:51:60: error: could not convert 'upd((l + 1), (a[(l + 1)] - a[l]), 1)' from 'void' to 'bool'
   51 |                 else a[l]=r,upd(l,a[l]-a[l-1],1),(l<n)&&upd(l+1,a[l+1]-a[l],1);
      |                                                         ~~~^~~~~~~~~~~~~~~~~~~