Change x.begin() to begin(x) (#96)

Author: Chillee

content/contest/template.cpp

@@ -3,7 +3,7 @@ using namespace std;
 
 #define rep(i, a, b) for(int i = a; i < (b); ++i)
 #define trav(a, x) for(auto& a : x)
-#define all(x) x.begin(), x.end()
+#define all(x) begin(x), end(x)
 #define sz(x) (int)(x).size()
 typedef long long ll;
 typedef pair<int, int> pii;