diff --git a/calc.c b/calc.c
new file mode 100644
index 0000000..2620da6
--- /dev/null
+++ b/calc.c
@@ -0,0 +1,188 @@
+#include <stdio.h>
+
+#include <stdlib.h>
+
+enum calculator_state {
+  NUMBER_FIRST,
+  NUMBER_SECOND,
+  RESULT
+};
+
+enum calculator_op {
+  NO_OP,
+  ADD,
+  SUB,
+  DIV,
+  MUL
+};
+struct calculator {
+  // 1 число
+  int num1;
+  // 2 число
+  int num2;
+  // 3 операция
+  enum calculator_op operation;
+  // 4 результат
+  int result;
+  // 5 состояние атомата
+  enum calculator_state state;
+};
+
+int main() {
+    struct calculator calc;
+    calc.state = NUMBER_FIRST;
+    calc.operation = NO_OP;
+    calc.num1 = 0;
+    calc.num2 = 0;
+    calc.result = 0;
+
+    int input;
+    while (1) {
+      scanf("%d", & input);
+      switch (calc.state) {
+      case NUMBER_FIRST:
+        switch (input) {
+        case 0:
+          calc.num1 = (calc.num1 * 10) + 7;
+          break;
+        case 1:
+          calc.num1 = (calc.num1 * 10) + 8;
+          break;
+        case 2:
+          calc.num1 = (calc.num1 * 10) + 9;
+          break;
+        case 3:
+          calc.operation = DIV;
+          calc.state = NUMBER_SECOND;
+          break;
+        case 4:
+          calc.num1 = (calc.num1 * 10) + 4;
+          break;
+        case 5:
+          calc.num1 = (calc.num1 * 10) + 5;
+          break;
+        case 6:
+          calc.num1 = (calc.num1 * 10) + 6;
+          break;
+        case 7:
+          calc.operation = MUL;
+          calc.state = NUMBER_SECOND;
+          break;
+        case 8:
+          calc.num1 = (calc.num1 * 10) + 1;
+          break;
+        case 9:
+          calc.num1 = (calc.num1 * 10) + 2;
+        case 10:
+          calc.num1 = (calc.num1 * 10) + 3;
+          break;
+        case 11:
+          calc.operation = SUB;
+          calc.state = NUMBER_SECOND;
+          break;
+        case 12:
+          calc.num1 = 0;
+          break;
+        case 13:
+          calc.state = NUMBER_FIRST;
+          calc.operation = NO_OP;
+          calc.num1 = 0;
+          calc.num2 = 0;
+          calc.result = 0;
+          break;
+        case 14:
+          break;
+        case 15:
+          calc.operation = ADD;
+          calc.state = NUMBER_SECOND;
+          break;
+        }
+        break;
+        printf("%d %d %d %d %d", calc.num1, calc.num2, calc.result, calc.operation, calc.state);
+
+      case NUMBER_SECOND:
+        switch (input) {
+        case 0:
+          calc.num2 = (calc.num2 * 10) + 7;
+          break;
+        case 1:
+          calc.num2 = (calc.num2 * 10) + 8;
+          break;
+        case 2:
+          calc.num2 = (calc.num2 * 10) + 9;
+          break;
+        case 3:
+
+          break;
+        case 4:
+          calc.num2 = (calc.num2 * 10) + 4;
+          break;
+        case 5:
+          calc.num2 = (calc.num2 * 10) + 5;
+          break;
+        case 6:
+          calc.num2 = (calc.num2 * 10) + 6;
+          break;
+        case 7:
+          break;
+        case 8:
+          calc.num2 = (calc.num2 * 10) + 1;
+          break;
+        case 9:
+          calc.num2 = (calc.num2 * 10) + 2;
+        case 10:
+          calc.num2 = (calc.num2 * 10) + 3;
+          break;
+        case 11:
+          break;
+        case 12:
+          calc.num2 = 0;
+          break;
+        case 13:
+          calc.state = NUMBER_FIRST;
+          calc.operation = NO_OP;
+          calc.num1 = 0;
+          calc.num2 = 0;
+          calc.result = 0;
+          break;
+        case 14:
+          switch (calc.operation) {
+          case ADD:
+            calc.result = calc.num1 + calc.num2;
+            calc.state = RESULT;
+            break;
+          case SUB:
+            calc.result = calc.num1 - calc.num2;
+            break;
+          case MUL:
+            calc.result = calc.num1 * calc.num2;
+            break;
+          case DIV:
+            calc.result = calc.num1 / calc.num2;
+            break;
+            return calc.result;
+          }
+          break;
+          break;
+        case 15:
+          break;
+        }
+        printf("%d %d %d %d %d", calc.num1, calc.num2, calc.result, calc.operation, calc.state);
+        break;
+
+      case RESULT:
+        switch (input) {
+        case 14:
+          calc.state = NUMBER_FIRST;
+          calc.operation = NO_OP;
+          calc.num1 = 0;
+          calc.num2 = 0;
+          calc.result = 0;
+          break;
+        }
+        break;
+        printf("%d %d %d %d %d", calc.num1, calc.num2, calc.result, calc.operation, calc.state);
+      }
+    }
+    return 0;
+}