#include <bits/stdc++.h>   using namespace std;   void __print(int x) { cerr << x; }   void __print(long x) { cerr << x; }   void __print(long long x) { cerr << x; }   void __print(unsigned x) { cerr << x; }   void __print(unsigned long x) { cerr << x; }   void __print(unsigned long long x) { cerr << x; }   void __print(float x) { cerr << x; }   void __print(double x) { cerr << x; }   void __print(long double x) { cerr << x; }   void __print(char x) { cerr <<      << x <<     ; }   void __print(const char *x) { cerr <<     << x <<    ; }   void __print(const string &x) { cerr <<     << x <<    ; }   void __print(bool x) { cerr << (x ?  true  :  false ); }   template <typename T, typename V>   void __print(const pair<T, V> &x) {     cerr <<  { ;     __print(x.first);     cerr <<  , ;     __print(x.second);     cerr <<  } ;   }   template <typename T>   void __print(const T &x) {     int f = 0;     cerr <<  { ;     for (auto &i : x) cerr << (f++ ?  ,  :   ), __print(i);     cerr <<  } ;   }   void _print() { cerr <<  ] n ; }   template <typename T, typename... V>   void _print(T t, V... v) {     __print(t);     if (sizeof...(v)) cerr <<  ,  ;     _print(v...);   }   const int N = 3e5 + 5;   long long a[N];   int main() {     ios_base ::sync_with_stdio(false);     cin.tie(NULL);     cout.tie(NULL);     string s;     cin >> s;     string open =  ([{< ;     string close =  )]}> ;     map<char, char> closeMp;     for (int i = 0; i < 4; i++) closeMp[close[i]] = open[i];     stack<char> st;     int ans = 0;     for (auto i : s) {       if (closeMp.count(i) == 0) {         st.push(i);       } else {         if (st.empty())           return cout <<  Impossible , 0;         else {           if (st.top() != closeMp[i]) ans++;           st.pop();         }       }     }     if (st.empty())       cout << ans;     else       cout <<  Impossible ;     return 0;   }   