#define _CRT_SECURE_NO_WARNINGS #define _USE_MATH_DEFINES #include "bits/stdc++.h" #define REP(i,a,b) for(i=a;i> a;}; template void reader(T& t, U& u) { reader(t); reader(u); } template void reader(T& t, U& u, V& v) { reader(t); reader(u); reader(v); } void writer(const int a, char c) { printf("%d", a); putchar(c); } void writer(const ll a, char c) { printf("%lld", a); putchar(c); } void writer(const ull a, char c) { printf("%llu", a); putchar(c); } void writer(const double a, char c) { printf("%.20lf", a); putchar(c); } void writer(const char a[]) { printf("%s", a); }; void writer(const char a[], char c) { printf("%s", a); putchar(c); }; void writer(const char a, char c) { putchar(a); putchar(c); }; template void writerLn(T t) { writer(t, '\n'); } template void writerLn(T t, U u) { writer(t, ' '); writer(u, '\n'); } template void writerLn(T t, U u, V v) { writer(t, ' '); writer(u, ' '); writer(v, '\n'); } template void writerArr(T x[], int n) { int i; if (!n) { putchar('\n'); return; }rep(i, n - 1) writer(x[i], ' '); writer(x[n - 1], '\n'); } template void writerVec(vector x) { int n = x.size(); int i; if (!n) { putchar('\n'); return; }rep(i, n - 1) writer(x[i], ' '); writer(x[n - 1], '\n'); } vector split(const string &str, char sep) { vector v; stringstream ss(str); string buffer; while (getline(ss, buffer, sep)) { v.push_back(buffer); }return v; } // #define int ll bool test = 0; int dx[] = { 0,1,0,-1 }; int dy[] = { 1,0,-1,0 }; #define INF (1 << 28) ull mod = (int)1e9 + 7; //..................... #define MAX (int)1e6 + 5 #define N 10 signed main(void) { int i, j, k, l; int A; cin >> A; int x = A - 7; if (x < 8) { cout << -1 << endl; return 0; } cout << x << endl; return 0; }