#include <iostream>
using namespace std;
const int MAX=255;
char a[MAX], s[MAX];
int k=0;
int main() {
    cin>>s;
    for(int i = 0; i <strlen(s); i++) {
        if (s[i]=='(' || s[i]=='[' || s[i]=='{') a[k++]=s[i];
        if ((s[i]==')' && a[k-1]=='(' || s[i]==']' && a[k-1]=='[' || s[i]=='}' && a[k-1]=='{') && k>0)k--;
    }
    if (k==0) cout<<"yes"; else cout<<"no";
    return 0;
}