diff --git a/conv/aprob_fprob.cc b/conv/aprob_fprob.cc
index d30b627..4babb93 100644
--- a/conv/aprob_fprob.cc
+++ b/conv/aprob_fprob.cc
@@ -33,20 +33,21 @@ static void Exec() {
 
   std::ifstream fmap_st {args::get(param::fmap)};
   Enforce(!!fmap_st, "fmap path is invalid");
-  const auto fmap = ReadMatrix<uint32_t>(fmap_st);
-  Enforce(fmap.size() > 0, "empty fmap");
-  for (auto& idxs : fmap) {
-    Enforce(idxs.size() > 0, "fmap has empty item");
+  const auto fmap = ReadTensor3<uint32_t>(fmap_st);
+  Enforce(fmap.size() > 0 && fmap[0].size() > 0, "empty fmap");
+  for (auto& fmap_t : fmap) {
+    Enforce(fmap_t.size() == fmap[0].size(), "fmap is broken");
   }
 
   for (size_t t = 0; t < aprobs.size(); ++t) {
-    Enforce(aprobs[t].size() <= fmap.size(), "unmatched aprobs and fmap");
-    for (size_t c = 0; c < fmap.size(); ++c) {
+    const auto tidx = t % fmap.size();
+    for (size_t c = 0; c < fmap[tidx].size(); ++c) {
       double sum = 0;
-      for (auto i : fmap[c]) {
+      for (auto i : fmap[tidx][c]) {
+        Enforce(i < aprobs[t].size(), "aprob has no enough columns");
         sum += aprobs[t][i];
       }
-      std::cout << sum / fmap[c].size() << ' ';
+      std::cout << sum / fmap[tidx][c].size() << ' ';
     }
     std::cout << '\n';
   }
diff --git a/conv/common.hh b/conv/common.hh
index 40a28d4..e635a68 100644
--- a/conv/common.hh
+++ b/conv/common.hh
@@ -17,7 +17,7 @@ inline void Enforce(bool eval, const std::string& msg) {
 }
 
 template <typename T>
-std::vector<std::vector<T>> ReadMatrix(std::istream& st) noexcept {
+auto ReadMatrix(std::istream& st) noexcept {
   std::vector<std::vector<T>> ret;
 
   std::string line;
@@ -28,6 +28,23 @@ std::vector<std::vector<T>> ReadMatrix(std::istream& st) noexcept {
   }
   return ret;
 }
+template <typename T>
+auto ReadTensor3(std::istream& st) noexcept {
+  std::vector<std::vector<std::vector<T>>> ret(1);
+
+  std::string line;
+  while (std::getline(st, line)) {
+    if (line == "----") {
+      ret.push_back({});
+    } else {
+      std::istringstream sst {line};
+      ret.back().emplace_back(std::istream_iterator<T> {sst},
+                              std::istream_iterator<T> {});
+    }
+  }
+  return ret;
+}
+
 
 
 // ---- MP4 utilities
diff --git a/conv/feat_block.cc b/conv/feat_block.cc
index 60af16d..695a42f 100644
--- a/conv/feat_block.cc
+++ b/conv/feat_block.cc
@@ -27,17 +27,16 @@ ValueFlag<std::string> fmap {
 static void Exec() {
   std::ifstream fmap_st {args::get(param::fmap)};
   Enforce(!!fmap_st, "fmap path is invalid");
-  const auto fmap = ReadMatrix<uint32_t>(fmap_st);
-  Enforce(fmap.size() > 0, "empty fmap");
-  for (auto& idxs : fmap) {
-    Enforce(idxs.size() > 0, "fmap has empty item");
+  const auto fmap = ReadTensor3<uint32_t>(fmap_st);
+  Enforce(fmap.size() > 0 && fmap[0].size() > 0, "empty fmap");
+  for (auto& fmap_t : fmap) {
+    Enforce(fmap_t.size() == fmap[0].size(), "fmap is broken");
   }
 
-  size_t feat;
-  while (std::cin >> feat) {
-    Enforce(feat < fmap.size(), "feat overflow");
-
-    for (const auto idx : fmap[feat]) {
+  for (size_t feat, t = 0; std::cin >> feat; ++t) {
+    const auto tidx = t % fmap.size();
+    Enforce(feat < fmap[tidx].size(), "feat overflow");
+    for (const auto idx : fmap[tidx][feat]) {
       std::cout << idx << ' ';
     }
     std::cout << '\n';