diff --git a/src/7/15/U306735.cpp b/src/7/15/U306735.cpp
new file mode 100644
index 0000000..d7c42bf
--- /dev/null
+++ b/src/7/15/U306735.cpp
@@ -0,0 +1,56 @@
+#include <algorithm>
+#include <cstdint>
+#include <iostream>
+#include <istream>
+#include <map>
+#include <string>
+#include <vector>
+
+using ll=int64_t;
+
+ll n{},m{};
+std::string s;
+std::vector<std::vector<ll>> edge;
+
+ll find(ll now,std::map<char, ll> &w,ll max,std::vector<bool> &vis){
+    if(vis[now]){
+        return -1;
+    }
+    vis[now]=true;
+    w[s[now]]++;
+    max=std::max(max,w[s[now]]);
+    for(ll nxt:edge[now]){
+        if(ll findr = find(nxt, w,max,vis);findr==-1){
+            return -1;
+        }else{
+            max=std::max(max,findr);
+        }
+    }
+    w[s[now]]--;
+    vis[now]=false;
+    return max;
+}
+
+int main(){
+    std::iostream::sync_with_stdio(false);
+    std::cin.tie(nullptr);
+    std::cout.tie(nullptr);
+
+    std::cin>>n>>m;
+    edge.resize(n+1);
+    std::cin>>s;
+    s=' '+s;
+    for(ll i=1;i<=m;i++){
+        ll u{},v{};
+        std::cin>>u>>v;
+        edge[u].push_back(v);
+    }
+
+    for(ll i=1;i<=n;i++){
+        ll ans{};
+        std::map<char, ll> w;
+        std::vector<bool> vis(n+1);
+        ans=find(i, w, 0,vis);
+        std::cout<<ans<<'\n';
+    }
+}
\ No newline at end of file
diff --git a/src/7/15/opt1.ans b/src/7/15/opt1.ans
new file mode 100644
index 0000000..5e31dea
--- /dev/null
+++ b/src/7/15/opt1.ans
@@ -0,0 +1,5 @@
+3
+1
+2
+1
+1
\ No newline at end of file
diff --git a/src/7/15/opt1.in b/src/7/15/opt1.in
new file mode 100644
index 0000000..2cbe2ab
--- /dev/null
+++ b/src/7/15/opt1.in
@@ -0,0 +1,6 @@
+5 4
+abaca
+1 2
+1 3
+3 4
+4 5
\ No newline at end of file
diff --git a/src/7/15/opt2.ans b/src/7/15/opt2.ans
new file mode 100644
index 0000000..6aa9b2f
--- /dev/null
+++ b/src/7/15/opt2.ans
@@ -0,0 +1,6 @@
+-1
+-1
+-1
+-1
+-1
+-1
\ No newline at end of file
diff --git a/src/7/15/opt2.in b/src/7/15/opt2.in
new file mode 100644
index 0000000..8b34b5d
--- /dev/null
+++ b/src/7/15/opt2.in
@@ -0,0 +1,8 @@
+6 6
+xzyabc
+1 2
+3 1
+2 3
+5 4
+4 3
+6 4
\ No newline at end of file
diff --git a/src/7/15/opt3.ans b/src/7/15/opt3.ans
new file mode 100644
index 0000000..cc7cd93
--- /dev/null
+++ b/src/7/15/opt3.ans
@@ -0,0 +1,10 @@
+4
+4
+2
+3
+1
+2
+1
+1
+1
+1
\ No newline at end of file
diff --git a/src/7/15/opt3.in b/src/7/15/opt3.in
new file mode 100644
index 0000000..0e960ab
--- /dev/null
+++ b/src/7/15/opt3.in
@@ -0,0 +1,16 @@
+10 14
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+3 5
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+2 10
+3 9
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+4 6
+1 10
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+3 7
\ No newline at end of file
diff --git a/src/7/15/opt4.ans b/src/7/15/opt4.ans
new file mode 100644
index 0000000..f08419a
--- /dev/null
+++ b/src/7/15/opt4.ans
@@ -0,0 +1,500 @@
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new file mode 100644
index 0000000..71ccd9b
--- /dev/null
+++ b/src/7/15/opt4.in
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