#include <bits/stdc++.h>
using namespace std;

#define _ ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define loop(i,b,e) for(auto i=b;i<=e;i++)
#define ALL(x) x.begin(),x.end()
#define SZ(x) x.size()
#define PB push_back
typedef vector<int> VI;

int n,a,b,cnt,x,ans;
string s;
VI v;

int main() {_
   cin >> n >> a >> b >> s;
   loop(i,0,s.length()) {
      if(s[i] == '.')
         cnt++;
      else if(cnt != 0) {
         v.PB(cnt);
         cnt = 0;
      }
   }
   sort(ALL(v),greater<int>());
   loop(i,0,SZ(v)-1) {
      if(a == 0 && b == 0)
         break;
      if(v[i] % 2 == 0) {
         x = min(v[i]/2,a);
         ans += x;
         a -= x;

         x = min(v[i]/2,b);
         ans += x;
         b -= x;
      }
      else {
         x = min(v[i]/2,b);
         ans += x;
         a -= x;

         x = min(v[i]/2,a);
         ans += x;
         b -= x;

         if(a > b && a >= 1)
            ans++,a--;
         else if(b > a && b >= 1)
            ans++,b--;
         else if(a >= 1 && b >= 1)
            ans++,a--;
      }
   }
   cout << ans;
}