View Compilation Error

0_0_22426656_23760.c:5:2: error: unknown type name 'node'
  node *lson;
  ^
0_0_22426656_23760.c:6:2: error: unknown type name 'node'
  node *rson;
  ^
0_0_22426656_23760.c:10:1: error: unknown type name 'node'
 node *Build(node* tree,int a){
 ^
0_0_22426656_23760.c:10:13: error: unknown type name 'node'
 node *Build(node* tree,int a){
             ^
0_0_22426656_23760.c:26:11: error: unknown type name 'node'
 void show(node *tree,int flag){
           ^
0_0_22426656_23760.c: In function 'main':
0_0_22426656_23760.c:37:2: error: unknown type name 'node'
  node *tree;
  ^
0_0_22426656_23760.c:42:3: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
   for (int i=0; i<t; i++){
   ^
0_0_22426656_23760.c:42:3: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code