Question about "iostream"

[Yile]

My C program runs well. But when I modify it to C++ version, it doesn't work. The reason is that I don't understand the "iostream" very well.
This is my program which is used to input a Tree from keyboard. For example:

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if the tree is:
    1
   /
  2
 / \
3   4

Then I can input :
 (1 (2 (3 () () ) (4 () () ) ) () )

This is my C program which is all right:

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#include <stdio.h>
int main(){
  char c;
  int left=0,right=0;
  int v;
  while(left>right || left==0){
    c=getchar();
    while(c!='(' && c!=')')
      c=getchar();
    if(c=='('){
      left++;
      putchar(c);
      if(scanf("%d",&v))
		printf("%d",v);
    }
    else{
      right++;
      putchar(c);
    }
  }
  return 0;
}

But the C++ version doesn't work:

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#include <iostream.h>
int main(){
  char c;
  int left=0,right=0;
  int v;
  while(left>right || left==0){
    cin.get(c);
    while(c!='(' && c!=')')
      cin.get(c);
    if(c=='('){
      left++;
      cout<<c;
      if(cin>>v)
		cout<<v;
    }
    else{
      right++;
      cout<<c;
    }
  }
  return 0;
}

What's the matter?