Problem p02833 (C++)

Buggy submission (status: Time Limit Exceeded):
// x<<y=x*2^y,x>>y=x/2^y
// 1<<31 gives overflow
// use ll() for using an integer in self-built fn
//(x&-x) bitwise and of (x and its 2's complement) returns (last set bit)
// eg if x=1010 then it will return 0010
//  careful dont print empty container(run time error)
// v.erase O(n)
// use ("\n") instead of endl as endl flushes the output buffer
// every time so takes more time than \n (TLE)
// stoll() and to_string((less than 1e19))
// INT_MAX is approx 3e10
// For sets use set_name.lower_bound(x)(strictly O(logn))
// NOT lb(all(s),x)(O(logn) for random access (eg vector) but for sets it is
// O(n));
#include <bits/stdc++.h>
typedef long long int ll;
#define ull unsigned long long int
#define lld long double
#define endl "\n"
#define fi first
#define sec second
#define sp setprecision
#define lb lower_bound
#define ub upper_bound
#define For(i, a, b) for (long long int i = (a); i <= (b); i++)
#define Forr(i, a, b) for (long long int i = (a); i >= (b); i--)
#define pb(a) push_back(a)
#define mp(a, b) make_pair(a, b)
#define vll vector<ll>
#define vlld vector<lld>
#define vi vector<int>
#define vch vector<char>
#define sll set<ll>
#define sch set<ch>
#define vpll vector<pair<ll, ll>>
#define vpii vector<pair<int, int>>
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define mll map<ll, ll>
#define mcll map<char, ll>
#define sz(container) ll((container).size())
#define fill(a, b) memset(a, b, sizeof(a))
#define fast_io ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL)
using namespace std;
lld pi = 3.1415926535897932;
const ll MOD = 1e9 + 7;
const ll dx[4] = {-1, 0, 1, 0}, dy[4] = {0, 1, 0, -1};
const ll dxx[8] = {-1, -1, 0, 1, 1, 1, 0, -1},
         dyy[8] = {0, 1, 1, 1, 0, -1, -1, -1};

/**************************************************
//FENWICK TREE
ll bit[100005];
void update(ll idx, ll val, ll n)
{
    for (; idx <= n; idx += idx&-idx)
        bit[idx] += val;
}
ll query(ll idx)
{
    ll sum = 0;
    for (; idx>0; idx-=idx&-idx)
        sum += bit[idx];
    return sum;
}
*****************************************************/

ll lcm(ll a, ll b) {
  ll g = __gcd(a, b);
  return a / g * b;
}

ll binpow(ll a, ll b, ll m) {
  a %= m;
  ll res = 1;
  while (b > 0) {
    if (b & 1)
      res = res * a % m;
    a = a * a % m;
    b >>= 1;
  }
  return res;
}
bool isPrime(ll n) {
  // Corner cases
  if (n <= 1)
    return false;
  if (n <= 3)
    return true;

  // This is checked so that we can skip
  // middle five numbers in below loop
  if (n % 2 == 0 || n % 3 == 0)
    return false;

  for (ll i = 5; i * i <= n; i = i + 6)
    if (n % i == 0 || n % (i + 2) == 0)
      return false;

  return true;
}
/******************************************
ll phi(ll n)
{
    ll result = n;
    For(i,0,sqrt(n))
    {
        if (n % i == 0)
        {
            while (n % i == 0)
                n /= i;
            result -= result / i;
        }
    }
    if (n > 1)
        result -= result / n;
    return result;
}
************************************/

/***************************************
//to check whether a string is whole number(without leading 0s)
bool isNumber(string s)
{
    if(s=="0") return true;
    if(s[0]=='0') return false;
    For(i,0,sz(s)-1)
    {
        if (isdigit(s[i]) == false)  return false;
    }
    return true;
}
******************************/
/******************************
queue<ll> q;
//p:parent d:depth
vll used(200002),p(200002),d(200002);
vector<vll>adj(200002);
void bfs(ll s)
{
    q.push(s);
    p[s] = -1;
    used[s] = 1;
    while (!q.empty())
    {
        ll v = q.front();
        q.pop();
        for (ll u : adj[v])
        {
            if (!used[u])
            {
                used[u] = 1;
                q.push(u);
                d[u] = d[v] + 1;
                p[u] = v;
            }
        }
    }
}
*****************************/
/***********************************

vector<vll >adj(100005);
vll subsz(100005);
void dfs(ll v,ll x)
{
    subsz[v]=1;
    for(ll u : adj[v])
    {
        if (u!=x) dfs(u,v),subsz[v]+=subsz[u];
    }
}
************************************/
/**********************************
ll used[1005][1005];
char s[1005][1005];
void dfs(ll x,ll y)
{
    used[x][y]=1;
    For(i,0,3)
    {
       ll nx=x+dx[i],ny=y+dy[i];
       if(used[nx][ny]==0&&s[nx][ny]!='#') dfs(nx,ny);
    }
}
*********/
int main() {

#ifndef ONLINE_JUDGE
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
#endif
  fast_io;
  ll T = 1; // cin>>T;
  For(i, 1, T) {
    ll n;
    cin >> n;
    ll c5 = 0, c2 = 0;
    for (ll j = n; j >= 1; j -= 2) {
      ll temp = j;
      while (temp % 2 == 0) {
        temp /= 2;
        c2++;
      }
      while (temp % 5 == 0) {
        temp /= 5;
        c5++;
      }
    }
    cout << min(c5, c2);
  }
}

Fixed submission:
// x<<y=x*2^y,x>>y=x/2^y
// 1<<31 gives overflow
// use ll() for using an integer in self-built fn
//(x&-x) bitwise and of (x and its 2's complement) returns (last set bit)
// eg if x=1010 then it will return 0010
//  careful dont print empty container(run time error)
// v.erase O(n)
// use ("\n") instead of endl as endl flushes the output buffer
// every time so takes more time than \n (TLE)
// stoll() and to_string((less than 1e19))
// INT_MAX is approx 3e10
// For sets use set_name.lower_bound(x)(strictly O(logn))
// NOT lb(all(s),x)(O(logn) for random access (eg vector) but for sets it is
// O(n));
#include <bits/stdc++.h>
typedef long long int ll;
#define ull unsigned long long int
#define lld long double
#define endl "\n"
#define fi first
#define sec second
#define sp setprecision
#define lb lower_bound
#define ub upper_bound
#define For(i, a, b) for (long long int i = (a); i <= (b); i++)
#define Forr(i, a, b) for (long long int i = (a); i >= (b); i--)
#define pb(a) push_back(a)
#define mp(a, b) make_pair(a, b)
#define vll vector<ll>
#define vlld vector<lld>
#define vi vector<int>
#define vch vector<char>
#define sll set<ll>
#define sch set<ch>
#define vpll vector<pair<ll, ll>>
#define vpii vector<pair<int, int>>
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define mll map<ll, ll>
#define mcll map<char, ll>
#define sz(container) ll((container).size())
#define fill(a, b) memset(a, b, sizeof(a))
#define fast_io ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL)
using namespace std;
lld pi = 3.1415926535897932;
const ll MOD = 1e9 + 7;
const ll dx[4] = {-1, 0, 1, 0}, dy[4] = {0, 1, 0, -1};
const ll dxx[8] = {-1, -1, 0, 1, 1, 1, 0, -1},
         dyy[8] = {0, 1, 1, 1, 0, -1, -1, -1};

/**************************************************
//FENWICK TREE
ll bit[100005];
void update(ll idx, ll val, ll n)
{
    for (; idx <= n; idx += idx&-idx)
        bit[idx] += val;
}
ll query(ll idx)
{
    ll sum = 0;
    for (; idx>0; idx-=idx&-idx)
        sum += bit[idx];
    return sum;
}
*****************************************************/

ll lcm(ll a, ll b) {
  ll g = __gcd(a, b);
  return a / g * b;
}

ll binpow(ll a, ll b, ll m) {
  a %= m;
  ll res = 1;
  while (b > 0) {
    if (b & 1)
      res = res * a % m;
    a = a * a % m;
    b >>= 1;
  }
  return res;
}
bool isPrime(ll n) {
  // Corner cases
  if (n <= 1)
    return false;
  if (n <= 3)
    return true;

  // This is checked so that we can skip
  // middle five numbers in below loop
  if (n % 2 == 0 || n % 3 == 0)
    return false;

  for (ll i = 5; i * i <= n; i = i + 6)
    if (n % i == 0 || n % (i + 2) == 0)
      return false;

  return true;
}
/******************************************
ll phi(ll n)
{
    ll result = n;
    For(i,0,sqrt(n))
    {
        if (n % i == 0)
        {
            while (n % i == 0)
                n /= i;
            result -= result / i;
        }
    }
    if (n > 1)
        result -= result / n;
    return result;
}
************************************/

/***************************************
//to check whether a string is whole number(without leading 0s)
bool isNumber(string s)
{
    if(s=="0") return true;
    if(s[0]=='0') return false;
    For(i,0,sz(s)-1)
    {
        if (isdigit(s[i]) == false)  return false;
    }
    return true;
}
******************************/
/******************************
queue<ll> q;
//p:parent d:depth
vll used(200002),p(200002),d(200002);
vector<vll>adj(200002);
void bfs(ll s)
{
    q.push(s);
    p[s] = -1;
    used[s] = 1;
    while (!q.empty())
    {
        ll v = q.front();
        q.pop();
        for (ll u : adj[v])
        {
            if (!used[u])
            {
                used[u] = 1;
                q.push(u);
                d[u] = d[v] + 1;
                p[u] = v;
            }
        }
    }
}
*****************************/
/***********************************

vector<vll >adj(100005);
vll subsz(100005);
void dfs(ll v,ll x)
{
    subsz[v]=1;
    for(ll u : adj[v])
    {
        if (u!=x) dfs(u,v),subsz[v]+=subsz[u];
    }
}
************************************/
/**********************************
ll used[1005][1005];
char s[1005][1005];
void dfs(ll x,ll y)
{
    used[x][y]=1;
    For(i,0,3)
    {
       ll nx=x+dx[i],ny=y+dy[i];
       if(used[nx][ny]==0&&s[nx][ny]!='#') dfs(nx,ny);
    }
}
*********/
int main() {

#ifndef ONLINE_JUDGE
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
#endif
  fast_io;
  ll T = 1; // cin>>T;
  For(i, 1, T) {
    ll n;
    cin >> n;
    ll ans = 0;
    ll temp = 5 * 2;
    while (1) {
      if ((n / temp) == 0)
        break;
      ans += (n / temp);
      temp *= 5;
    }
    if (n % 2)
      ans = 0;
    cout << ans;
  }
}