import std.stdio;
int solve (int area) {
int res = 6, total = 1;
while (true)
foreach (p; 0..6) {
if (total >= area) return res;
res += 1;
total += res / 6 - !p;
}
}
void main () {
int n;
readf (" %s", &n);
writeln (solve (n));
}
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