#include<iostream>
#include<vector>
using namespace std;
#define int long long
int N, F, T;
vector<int> num(102);
signed main() {
cin>>N>>F>>T;
int sum = 0;
int now = 0;
int ans = 0;
for(int i=1; i<=N; i++) {cin>>num[i]; sum+=num[i]; if(i<=F) now += num[i];}
if(T>F) {cout<<"NO"; return 0;}
else if(T>sum) {cout<<"NO"; return 0;}
while(now<T) {
for(int i=F; i>=0; i--) {
if(num[i] == 0) {
for(int j=i; j<F; j++) {
swap(num[j],num[j+1]);
ans++;
}
break;
}
}
for(int i = F+1; i<=N; i++) {
if(num[i] == 1){
for(int j = i; j>F; j--) {
swap(num[j],num[j-1]);
ans++;
}
}
break;
}
swap(num[F], num[F+1]);
ans++;
now++;
}
cout<<ans;
}
