View Compilation Error

0_0_30401828_31202.cpp: In function 'void Update(int, int, int, int, int, int)':
0_0_30401828_31202.cpp:34:9: error: 'mid' was not declared in this scope
   if(a<=mid)Update(a,b,c,lson);
         ^
0_0_30401828_31202.cpp:35:8: error: 'mid' was not declared in this scope
   if(b>mid)Update(a,b,c,rson);
        ^