1 #include<algorithm>
  2 #include<iostream>
  3 #include<istream>
  4 #include<ostream>
  5 #include<cstdlib>
  6 #include<cstring>
  7 #include<cassert>
  8 #include<cstdio>
  9 #include<string>
 10 using std::max;
 11 using std::cin;
 12 using std::cout;
 13 using std::endl;
 14 using std::swap;
 15 using std::string;
 16 using std::istream;
 17 using std::ostream;
 18 struct BigN {
 19     typedef unsigned long long ull;
 20     static const int Max_N = 36000;
 21     int len, data[Max_N];
 22     BigN() { memset(data, 0, sizeof(data)), len = 0; }
 23     BigN(const int num) {
 24         memset(data, 0, sizeof(data));
 25         *this = num;
 26     }
 27     BigN(const char *num) {
 28         memset(data, 0, sizeof(data));
 29         *this = num;
 30     }
 31     void cls() { len = 0, memset(data, 0, sizeof(data)); }
 32     BigN& clean(){ while (len > 1 && !data[len - 1]) len--;  return *this; }
 33     string str() const {
 34         string res = "";
 35         for (int i = len - 1; ~i; i--) res += (char)(data[i] + ‘0‘);
 36         if (res == "") res = "0";
 37         res.reserve();
 38         return res;
 39     }
 40     BigN operator = (const int num) {
 41         int j = 0, i = num;
 42         do data[j++] = i % 10; while (i /= 10);
 43         len = j;
 44         return *this;
 45     }
 46     BigN operator = (const char *num) {
 47         len = strlen(num);
 48         for (int i = 0; i < len; i++) data[i] = num[len - i - 1] - ‘0‘;
 49         return *this;
 50     }
 51     BigN operator + (const BigN &x) const {
 52         BigN res;
 53         int n = max(len, x.len) + 1;
 54         for (int i = 0, g = 0; i < n; i++) {
 55             int c = data[i] + x.data[i] + g;
 56             res.data[res.len++] = c % 10;
 57             g = c / 10;
 58         }
 59         while (!res.data[res.len - 1]) res.len--;
 60         return res;
 61     }
 62     BigN operator * (const BigN &x) const {
 63         BigN res;
 64         int n = x.len;
 65         res.len = n + len;
 66         for (int i = 0; i < len; i++) {
 67             for (int j = 0, g = 0; j < n; j++) {
 68                 res.data[i + j] += data[i] * x.data[j];
 69             }
 70         }
 71         for (int i = 0; i < res.len - 1; i++) {
 72             res.data[i + 1] += res.data[i] / 10;
 73             res.data[i] %= 10;
 74         }
 75         return res.clean();
 76     }
 77     BigN operator * (const int num) const {
 78         BigN res;
 79         res.len = len + 1;
 80         for (int i = 0, g = 0; i < len; i++) res.data[i] *= num;
 81         for (int i = 0; i < res.len - 1; i++) {
 82             res.data[i + 1] += res.data[i] / 10;
 83             res.data[i] %= 10;
 84         }
 85         return res.clean();
 86     }
 87     BigN operator - (const BigN &x) const {
 88         assert(x <= *this);
 89         BigN res;
 90         for (int i = 0, g = 0; i < len; i++) {
 91             int c = data[i] - g;
 92             if (i < x.len) c -= x.data[i];
 93             if (c >= 0) g = 0;
 94             else g = 1, c += 10;
 95             res.data[res.len++] = c;
 96         }
 97         return res.clean();
 98     }
 99     BigN operator / (const BigN &x) const {
100         return *this;
101     }
102     BigN operator += (const BigN &x) { return *this = *this + x; }
103     BigN operator *= (const BigN &x) { return *this = *this * x; }
104     BigN operator -= (const BigN &x) { return *this = *this - x; }
105     BigN operator /= (const BigN &x) { return *this = *this / x; }
106     bool operator <  (const BigN &x) const {
107         if (len != x.len) return len < x.len;
108         for (int i = len - 1; ~i; i--) {
109             if (data[i] != x.data[i]) return data[i] < x.data[i];
110         }
111         return false;
112     }
113     bool operator >(const BigN &x) const { return x < *this; }
114     bool operator<=(const BigN &x) const{ return !(x < *this); }
115     bool operator>=(const BigN &x) const{ return !(*this < x); }
116     bool operator!=(const BigN &x) const{ return x < *this || *this < x; }
117     bool operator==(const BigN &x) const{ return !(x < *this) && !(x > *this); }
118 };
119 istream& operator >> (istream &in, BigN &x) {
120     string src;
121     in >> src;
122     x = src.c_str();
123     return in;
124 }
125 ostream& operator << (ostream &out, const BigN &x) {
126     out << x.str();
127     return out;
128 }
129 int main() {
130 #ifdef LOCAL
131     freopen("in.txt", "r", stdin);
132     freopen("out.txt", "w+", stdout);
133 #endif
134     int n;
135     while (~scanf("%d", &n)) {
136         BigN res = 1;
137         if (0 == n || 1 == n) {
138             puts("1");
139             continue;
140         }
141         for (int i = 1; i <= n; i++) res *= i;
142         cout << res << endl;
143     }
144     return 0;
145 }