View Compilation Error

0_0_33449781_15759.cpp: In function 'void Update(int, int, int, int)':
0_0_33449781_15759.cpp:44:13: error: 'U' was not declared in this scope
  if(R<=mid) U
             ^
0_0_33449781_15759.cpp:44:13: error: expected '}' at end of input