#include <stdio.h>

int nzero ( int n ) {
    int s = 0;
    for (int i = 5; i<n; i*=5) {
        s += n/i;
    }    
    return s;
}    

int bsearch(int val)   
{
    int i, step;
    const int N = 1000000000;
    for (step = 1; step < N; step <<= 1);
    for (i = 0; step; step >>= 1) {
        if (i + step < N && nzero(i + step) <= val)
           i += step;
    }   
    while (nzero(i-1) == val) --i; 
    return i;
}


int main() {
    freopen("fact.in","r",stdin);
    freopen("fact.out","w",stdout);
    
    int n;
    scanf("%d",&n);
    int r = bsearch(n);
    printf("%d\n",r);
    return 0;
}