diff --git a/src/P2822/P2822_prefix.cpp b/src/P2822/P2822_prefix.cpp
index 4115f17..d40889c 100644
--- a/src/P2822/P2822_prefix.cpp
+++ b/src/P2822/P2822_prefix.cpp
@@ -4,8 +4,7 @@
 using ull = unsigned long long;
 
 static constexpr size_t max_n {(size_t)2e3+5}; 
-
-ull k, c[max_n][max_n], prefix[max_n][max_n], t, n, m;
+static ull k, c[max_n][max_n], prefix[max_n][max_n], t, n, m;
 
 static void init(){
     c[0][0] = c[1][0] = c[1][1] = 1;
@@ -15,7 +14,7 @@ static void init(){
             c[i][j] = (c[i-1][j-1] + c[i-1][j])%k;
         }
     }
-    for(ull i {2};i<max_n;i++){ //t被修改
+    for(ull i = 2;i<max_n;i++){ //t被修改
         for(ull j{1};j<=i;j++){
             prefix[i][j] = prefix[i-1][j]+prefix[i][j-1]-prefix[i-1][j-1] + (c[i][j]==0?1:0);
         }