http://codeforces.com/contest/1165/problem/A
#include<bits/stdc++.h>
using namespace std;
char c[500000];
int x,y,l,ans;
int main() {
scanf("%d%d%d", &l, &x, &y);
scanf("%s", c + 1);
for (int i = l; i > l - x; i--) {
if (i != l - y && c[i] == '1') ans++;
}
if (l - y >= 1 && c[l - y] == '0') ans++;
printf("%d\n", ans);
}