7485: [CSES Problem Set] Trailing Zeros
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Description
Your task is to calculate the number of trailing zeros in the factorial $n!$.
For example, 20!=2432902008176640000 and it has $4$ trailing zeros.
For example, 20!=2432902008176640000 and it has $4$ trailing zeros.
Input
The only input line has an integer $n$.
Output
Print the number of trailing zeros in $n!$.
Constraints
$1≤n≤10^9$
Sample 1 Input
20
Sample 1 Output
4
20!=2432902008176640000
Sample 2 Input
1
Sample 2 Output
0
1!=1
Sample 3 Input
5
Sample 3 Output
1
5!=120
HINT
相同题目：CSES 1618。