#include <cstdio>

long long cit() {
    long long ans = 0;
    char c = getchar();
    bool neg = false;
    while (c < '0' || c > '9') {
        if (c == '-') {
            c = getchar();
            neg = true;
            break;
        }
        c = getchar();
    }
    while (c >= '0' && c <= '9') {
        ans = (ans << 3) + (ans << 1) + (c - '0');
        c = getchar();
    }
    return (neg) ? -ans : ans;
}

void afis(long long n) {
    int l = 0;
    char c[20];
    if (n == 0) {
        putchar('0');
    }
    if (n < 0) {
        putchar('-');
        n = -n;
    }
    while (n > 0) {
        c[l++] = n % 10 + '0';
        n /= 10;
    }
    for (int i = l - 1; i >= 0; i--) {
        putchar(c[i]);
    }
    putchar('\n');
}


int main() {
    freopen("fact.in", "r", stdin);
 //   freopen("fact.out", "w", stdout);

    int p = cit();
    if (p == 0) {
        afis(1);
        return 0;
    }
    int st = 0, dr = 5 * p, ans;
    bool g = false;
    while (st <= dr) {
        int mij = (st + dr) / 2;
        int t = 0, aux = mij;
        while (aux >= 5) {
            aux /= 5;
            t += aux;
        }
        if (t == p) {
            g = true;
            ans = mij;
            break;
        }
        if (t < p) {
            st = mij + 1;
        } else {
            dr = mij - 1;
        }
    }
    ans = 5 * (ans / 5);
    afis((g) ? ans : -1);

    return 0;
}