View Compilation Error

0_0_26353744_9449.cpp:29:1: error: 'segTree' does not name a type
 segTree[N<<2];
 ^
0_0_26353744_9449.cpp: In function 'void build(int, int, int)':
0_0_26353744_9449.cpp:35:21: error: 'segTree' was not declared in this scope
         scanf("%d",&segTree[i]);
                     ^
0_0_26353744_9449.cpp:41:5: error: 'segTree' was not declared in this scope
     segTree[i]=segTree[i<<1]+segTree[(i<<1)|1];
     ^
0_0_26353744_9449.cpp: In function 'void update(int, int, int, int, int)':
0_0_26353744_9449.cpp:45:5: error: 'segTree' was not declared in this scope
     segTree[i]+=val;
     ^
0_0_26353744_9449.cpp: In function 'int query(int, int, int, int, int)':
0_0_26353744_9449.cpp:53:27: error: 'segTree' was not declared in this scope
     if(L==l&&R==r) return segTree[i];
                           ^