#include <bits/stdc++.h>
using namespace std;
char s[200005];
int main() {
  int l, t;
  scanf("%d %d", &l, &t);
  scanf("%s", s + 1);
  s[0] = '0';
  for (int i = 0; i <= l; i++) {
    if (s[i] == '.') {
      for (int j = i + 1; j <= l; j++)
        if (s[j] >= '5') {
          s[j] = 0;
          bool roundup = true;
          t--;
          for (int k = j - 1; k > i; k--) {
            if (roundup) {
              s[k]++;
              if (s[k] >= '5' && t) {
                s[k] = 0;
                t--;
                roundup = true;
              } else
                roundup = false;
            }
          }
          if (roundup) {
            s[i] = 0;
            for (int k = i - 1; k >= 0; k--) {
              s[k]++;
              if (s[k] <= '9')
                break;
              else
                s[k] = '0';
            }
          }
          break;
        }
    }
  }
  if (s[0] != '0') {
    printf("%s\n", s);
  } else {
    printf("%s\n", s + 1);
  }
}
