C++ :

#include<iostream>
#include<stack>
#include<cstring>
#include<cstdio>
using namespace std;
string s;
stack<int> number;
stack<char> symbol;
int get_pre(char,bool);
bool is_operator(char);
void my_calc();
void work();
int main()
{
	//freopen("test.in","r",stdin);
	//freopen("test.out","w",stdout);
	cin>>s;
	work();
	return 0;
}
bool is_operator(char ch)
{
	if(ch=='+'||ch=='-'||ch=='*'||ch=='/'||ch==')'||ch=='(')return true;
	else return false;
}
int get_pre(char ch,bool flag)
{
	if(ch=='+'||ch=='-')return 1;
	if(ch=='/'||ch=='*')return 2;
	if(ch=='('&&flag)return 0;
	if(ch=='('&&!flag)return 3;
	return 4;
}
void my_calc()
{
	int y=number.top();
	number.pop();
	if(symbol.top()=='+') number.top()+=y;
	if(symbol.top()=='-') number.top()-=y;
	if(symbol.top()=='*') number.top()*=y;
	if(symbol.top()=='/') number.top()/=y;				
	symbol.pop();
}
void work()
{
	int i=0;
	while(i<s.size())
	{
		if(!is_operator(s[i]))
		{
			int x=0;
			while(i<s.size()&&!is_operator(s[i]))
			{				
				x=x*10+s[i]-48;
				i++;
			}		
			number.push(x);	
			continue;	
		}
		
		if(s[i]=='(')
		{
			symbol.push(s[i]);
			i++;
			continue;
		} 
		if(s[i]==')')
		{
			while(symbol.top()!='(')
			{
				my_calc();
			}
			symbol.pop();
			++i;
			continue;
		}
		while(!symbol.empty()&&get_pre(s[i],false)<=get_pre(symbol.top(),true))
		{
			my_calc();
		}
		symbol.push(s[i]);
		i++;
	}	
	while(!symbol.empty())
	{
		my_calc();
	}
	cout<<number.top()<<endl;
}