[Init] Solved solutions

cs/787A.cs

@@ -0,0 +1,43 @@
+using System;
+
+namespace _787A
+{
+	class Program
+	{
+		static void Main(string[] args)
+		{
+			int[] a = Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
+			int[] b = Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
+			if ((a[1] - b[1]) % GCD(a[0], b[0]) == 0)
+			{
+				while (a[1] != b[1])
+				{
+					if (a[1] < b[1])
+					{
+						a[1] += a[0];
+					}
+					else
+					{
+						b[1] += b[0];
+					}
+				}
+				Console.WriteLine(a[1]);
+			}
+			else
+			{
+				Console.WriteLine(-1);
+			}
+		}
+		static int GCD(int a, int b)
+		{
+			int t;
+			while (b != 0)
+			{
+				t = a % b;
+				a = b;
+				b = t;
+			}
+			return a;
+		}
+	}
+}