import decimal
from math import ceil, floor, inf, log
n = input()
if n=='1':
print(1)
exit()
decimal.getcontext().prec = len(n)+6
decimal.getcontext().Emax = len(n)+6
log3 = log(10)*(len(n)-1)/log(3)
pref = n
if len(pref)>20:
pref = pref[:20]
pref = pref[0] + '.' + pref[1:]
log3 += log(float(pref))/log(3)
log3+=1e-8
full = max(0, floor(log3))
small=0
if full>=1 and log3-full<=log(2)/log(3)*2-1:
small=2
full-=1
elif log3-full<=log(2)/log(3):
small = 1
else:
full+=1
n = decimal.Decimal(n)
ans = full*3 + small*2
def check(f,s):
global ans
res = decimal.Decimal(3)**f * (2**s)
if res>=n:
ans = min(ans,f*3+s*2)
if small==0 and full>=1:
full-=1
small+=1
check(full,small)
elif small==1 and full>=1:
full-=1
small+=1
check(full,small)
elif small==2:
small-=2
full+=1
check(full,small)
print(ans)#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
#define rep(i,a,b) for (int i=(a); i<=(b); ++i)
#define per(i,a,b) for (int i=(a); i>=(b); --i)
const int N = 1500005, oo = 0x3f3f3f3f;
const double eps = 1e-8;
int pp[] = {0, 100030001, 100060001, 113111311, 114535411}, delta = 1000000;
char st[N];
int n, ans = oo;
int pow(int x, int k, int p) {
int res = 1;
for ( ; k; k >>= 1, x = (ll)x * x % p) {
if (k & 1) {
res = (ll)res * x % p;
}
}
return res;
}
struct BigInt {
vi v;
BigInt(char st[], int n) {
v.resize(n);
rep(i, 0, n-1) {
v[i] = st[n-1-i] - '0';
}
}
inline void detrail() {
while (!v.empty() && !v.back()) v.pop_back();
}
inline void comein() {
v.push_back(0);
for (int i = 0; i + 1 < (int)v.size(); ++i) {
v[i+1] += v[i] / 10;
v[i] %= 10;
}
detrail();
}
inline void add_one() {
v[0]++;
comein();
}
inline int hash(int p) {
ll x = 0;
per(i, (int)v.size() - 1, 0) {
x = x * 10 + v[i];
x %= p;
}
return x;
}
inline void div_2() {
if (v[0] & 1) add_one();
v[0] >>= 1;
for (int i = 0; i + 1 < (int)v.size(); ++i) {
v[i] += (v[i+1] & 1) * 5;
v[i+1] >>= 1;
}
detrail();
}
inline int log_3() {
int l = min(15, (int)v.size());
ll x = 0;
per(i, (int)v.size() - 1, (int)v.size() - l) {
x = x * 10 + v[i];
}
double w = (log(x) + ((int)v.size() - l) * log(10)) / log(3);
int t = w, cnt = 0;
t += (t + 1 - w < eps);
rep(i, 1, 4) {
int xx = pow(3, t, pp[i]), yy = hash(pp[i]);
cnt += (xx - yy > 0 && xx - yy <= delta);
}
if (cnt == 4) --t;
rep(i, 1, 4) {
if (pow(3, t, pp[i]) != hash(pp[i])) {
return t + 1;
}
}
return t;
}
};
int main() {
scanf("%s", st);
n = strlen(st);
if (n == 1 && st[0] == '1') {
printf("1\n");
return 0;
}
BigInt x = BigInt(st, n);
ans = x.log_3() * 3;
rep(i, 1, 2) {
x.div_2();
ans = min(ans, x.log_3() * 3 + i * 2);
}
printf("%d\n",ans);
return 0;
}/*1695734992.273435*/165B - Burning Midnight Oil | 17A - Noldbach problem |
1350A - Orac and Factors | 1373A - Donut Shops |
26A - Almost Prime | 1656E - Equal Tree Sums |
1656B - Subtract Operation | 1656A - Good Pairs |
1367A - Short Substrings | 87A - Trains |
664A - Complicated GCD | 1635D - Infinite Set |
1462A - Favorite Sequence | 1445B - Elimination |
1656C - Make Equal With Mod | 567A - Lineland Mail |
1553A - Digits Sum | 1359B - New Theatre Square |
766A - Mahmoud and Longest Uncommon Subsequence | 701B - Cells Not Under Attack |
702A - Maximum Increase | 1656D - K-good |
1426A - Floor Number | 876A - Trip For Meal |
1326B - Maximums | 1635C - Differential Sorting |
961A - Tetris | 1635B - Avoid Local Maximums |
20A - BerOS file system | 1637A - Sorting Parts |