Avoid warnings in FastInput

Author: simonlindholm

content/various/FastInput.h

@@ -13,10 +13,10 @@
 
 struct GC {
 	char buf[1 << 16];
-	int bc = 0, be = 0;
+	size_t bc = 0, be = 0;
 	char operator()() {
 		if (bc >= be) {
-			buf[0] = bc = 0;
+			buf[0] = 0, bc = 0;
 			be = fread(buf, 1, sizeof(buf), stdin);
 		}
 		return buf[bc++]; // returns 0 on EOF