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

template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}

//INSERT ABOVE HERE
Int dp[333][333][333];
signed main(){
  Int g,c,p;
  string s;
  cin>>g>>c>>p>>s;
  Int n=s.size();
  memset(dp,-1,sizeof(dp));
  dp[0][0][0]=0;
  for(Int i=0;i<n;i++){
    for(Int x=0;x<=g;x++){
      for(Int y=0;y<=c;y++){
	Int z=i-(x+y);
	if(z<0||i<z) continue;
	chmax(dp[i+1][x+1][y],dp[i][x][y]+(s[i]=='C')*3+(s[i]=='G'));
	chmax(dp[i+1][x][y+1],dp[i][x][y]+(s[i]=='P')*3+(s[i]=='C'));
	chmax(dp[i+1][x][y],dp[i][x][y]+(s[i]=='G')*3+(s[i]=='P'));		
      }
    }
  }
  cout<<dp[n][g][c]<<endl;
  return 0;
}