#include <bits/stdc++.h>
#define rep(i, n) for(int i=0;i<(int)(n);++i)
#define rep1(i, n) for(int i=1;i<=(int)(n);++i)
#define irep(i, a, n) for(int i=a;i<(int)(n);++i)
#define rrep(i, n) for(int i=(int)(n)-1;i>=0;--i)
#define rrep1(i, n) for(int i=(int)(n);i>=1;--i)
#define allrep(V, v) for(auto&& V:v)
#define all(x) (x).begin(),(x).end()
typedef long long lint;
const int INF=1<<29;
const double EPS=1e-9;
using namespace std;


int main (void)
{
  int n,k; cin>>n>>k;
  string s; cin>>s;
  int buy=0,free=0;
  if(k<=n){
    rep(i,k){
      if(free > 0) --free;
      else ++buy;
      if(s[i] == '1') free+=1;
      if(s[i] == '2') free+=2;
    }
    cout<<buy<<endl;
    return 0;
  }

  rep(i,n){
    if(free > 0) --free;
    else ++buy;
    if(s[i] == '1') free+=1;
    if(s[i] == '2') free+=2;
  }
  if(free>=n){
    cout<<buy<<endl;
    return 0;
  }

  int onebox_buy=buy,onebox_extra_free=free;
  int boxnum=k/n;
  buy=0;
  free=onebox_extra_free;
  rep(i,k%n){
    if(free > 0) --free;
    else ++buy;
    if(s[i] == '1') free+=1;
    if(s[i] == '2') free+=2;
  }

  cout<<onebox_buy+(onebox_buy-onebox_extra_free)*(boxnum-1)+buy<<endl;
  return 0;
}