#include <stdio.h>

long factorial(int n){
if (n == 0) return 1;
else return (n - n%25)*5;
}

int main()
{
    long a,b;
    FILE *f;
    FILE *g;
    int t;	
    f = fopen("euclid2.in","r");
    g = fopen("euclid2.out","w");
    fscanf(f,"%d",&t);
    fprintf(f,"%ld",factorial(t));
    fclose(g);
    fclose(f);
    return 0;
}
1 -- 5
2 -- 10
3 -- 15
4 -- 20