StandardToken first version

contracts/SafeMath.sol

@@ -0,0 +1,28 @@
+pragma solidity ^0.4.0;
+
+/**
+ * Math operations with safety checks
+ */
+contract SafeMath {
+  function safeMul(uint a, uint b) internal returns (uint) {
+    uint c = a * b;
+    assert(a == 0 || c / a == b);
+    return c;
+  }
+
+  function safeSub(uint a, uint b) internal returns (uint) {
+    assert(b <= a);
+    return a - b;
+  }
+
+  function safeAdd(uint a, uint b) internal returns (uint) {
+    uint c = a + b;
+    assert(c>=a && c>=b);
+    return c;
+  }
+
+  function assert(bool assertion) internal {
+    if (!assertion) throw;
+  }
+}
+