diff --git a/atcoder/abc051/A/main.cpp b/atcoder/abc051/A/main.cpp
new file mode 100644
index 00000000..40a7a3e8
--- /dev/null
+++ b/atcoder/abc051/A/main.cpp
@@ -0,0 +1,17 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = long long;
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    string s;
+    cin >> s;
+    s[5] = ' ';
+    s[13] = ' ';
+    cout << s << endl;
+
+    return 0;
+}
\ No newline at end of file
diff --git a/atcoder/abc051/B/main.cpp b/atcoder/abc051/B/main.cpp
new file mode 100644
index 00000000..1212f06b
--- /dev/null
+++ b/atcoder/abc051/B/main.cpp
@@ -0,0 +1,23 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = long long;
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    int K, S;
+    cin >> K >> S;
+    
+    int ans = 0;
+    for (int x = 0; x <= K; ++x) {
+        for (int y = 0; y <=K; ++y) {
+            int z = S - (x + y);
+            if (z <= K && z >= 0) ++ans;
+        }
+    }
+    cout << ans << endl;
+
+    return 0;
+}
\ No newline at end of file
diff --git a/atcoder/abc051/C/main.cpp b/atcoder/abc051/C/main.cpp
new file mode 100644
index 00000000..7266a042
--- /dev/null
+++ b/atcoder/abc051/C/main.cpp
@@ -0,0 +1,37 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = long long;
+
+int sx, sy, tx, ty;
+
+string solve() {
+    int W = tx - sx, H = ty - sy;
+    assert(W > 0 && H > 0);
+
+    vector<char> route;
+    for (int x = 0; x < W; ++x) route.push_back('R');
+    for (int y = 0; y < H; ++y) route.push_back('U');
+    for (int x = 0; x < W; ++x) route.push_back('L');
+    for (int y = 0; y < H; ++y) route.push_back('D');
+    route.push_back('D');
+    for (int x = 0; x < W + 1; ++x) route.push_back('R');
+    for (int y = 0; y < H + 1; ++y) route.push_back('U');
+    route.push_back('L');
+    route.push_back('U');
+    for (int x = 0; x < W + 1; ++x) route.push_back('L');
+    for (int y = 0; y < H + 1; ++y) route.push_back('D');
+    route.push_back('R');
+
+    return string(route.begin(), route.end());
+}
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    cin >> sx >> sy >> tx >> ty;
+    cout << solve() << endl;
+
+    return 0;
+}
\ No newline at end of file
diff --git a/atcoder/abc051/D/main.cpp b/atcoder/abc051/D/main.cpp
new file mode 100644
index 00000000..a191c405
--- /dev/null
+++ b/atcoder/abc051/D/main.cpp
@@ -0,0 +1,56 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = long long;
+
+const int inf = 1e7;
+int N, M;
+vector<vector<int>> G;
+vector<vector<int>> O;
+
+int solve() {
+    // COPY
+    O = G;
+
+    for (int k = 0; k < N; ++k) {
+        for (int i = 0; i < N; ++i) {
+            for (int j = 0; j < N; ++j) {
+                if (G[i][k] == inf || G[k][j] == inf) continue;
+                if (G[i][k] + G[k][j] < G[i][j]) {
+                    G[i][j] = G[i][k] + G[k][j];
+                }
+            }
+        }
+    }
+
+    int ans = 0;
+    for (int i = 0; i < N; ++i) {
+        for (int j = i + 1; j < N; ++j) {
+            if (i == j || O[i][j] == inf) continue;
+            bool use = false;
+            for (int s = 0; s < N; ++s) {
+                if (G[s][i] + O[i][j] == G[s][j]) use = true;
+            }
+            if (!use) ++ans;
+        }
+    }
+    return ans;
+}
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    cin >> N >> M;
+    G.assign(N, vector<int>(N, inf));
+    for (int i = 0; i < N; ++i) G[i][i] = 0;
+    for (int i = 0; i < M; ++i) {
+        int a, b, c;
+        cin >> a >> b >> c;
+        --a, --b;
+        G[a][b] = G[b][a] = c;
+    }
+    cout << solve() << endl;
+
+    return 0;
+}
\ No newline at end of file