diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..723ef36
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+.idea
\ No newline at end of file
diff --git a/geometry.cpp b/geometry.cpp
new file mode 100644
index 0000000..11e2cb1
--- /dev/null
+++ b/geometry.cpp
@@ -0,0 +1,49 @@
+#include "geometry.h"
+#include <math.h>
+#include "ternary_search.h"
+
+Point::Point(double a, double b, double c) : x (a), y (b), z (c) {}
+
+Point::Point() : x (0), y (0), z (0) {}
+
+Segment::Segment (const Point& a, const Point& b) {
+    one = a;
+    two = b;
+}
+
+
+// расстояние между точками
+const double getDistance(const Point& one, const Point& two) {
+    return sqrt(pow((one.x - two.x), 2) + pow((one.y - two.y), 2) + pow((one.z - two.z), 2));
+}
+
+Point operator+(const Point& one, const Point& two) {
+    return Point(one.x + two.x, one.y + two.y, one.z + two.z);
+}
+
+Point operator*(const Point& p, double mult) {
+    return Point(p.x * mult, p.y * mult, p.z * mult);
+}
+
+Point operator/(const Point& p, double mult) {
+    return Point(p.x / mult, p.y / mult, p.z / mult);
+}
+
+double getDistancePointToSegment(const Point& p, const Segment& seg, double eps) {
+    auto func = [&p](const Point& p_to) {
+        return getDistance(p_to, p);
+    };
+    // 1ый аргумент - точка, до которой кратчайшее растояние от p, 2ой - p
+    Point least_p_in_seg = ternarySearchMin(seg.one, seg.two, func, getDistance, eps);
+    return getDistance(least_p_in_seg, p);
+}
+
+
+double getDistanceSegmentToSegment(const Segment& seg1, const Segment& seg2, double eps) {
+    auto func = [&seg2](const Point& p_to) {
+        return getDistancePointToSegment(p_to, seg2);
+    };
+    // 1ый аргумент - точка, до которой кратчайшее растояние от p, 2ой - p
+    Point x = ternarySearchMin(seg1.one, seg1.two, func, getDistance, eps);
+    return getDistancePointToSegment(x, seg2);
+}
diff --git a/geometry.h b/geometry.h
new file mode 100644
index 0000000..347c2b8
--- /dev/null
+++ b/geometry.h
@@ -0,0 +1,34 @@
+#ifndef INC_3TERM_CONTESTS_GEOMETRY_H
+#define INC_3TERM_CONTESTS_GEOMETRY_H
+
+
+struct Point {
+    double x, y, z;
+
+    Point (double a, double b, double c);
+
+    Point ();
+};
+
+struct Segment {
+    Point one, two;
+
+    Segment (const Point& a, const Point& b);
+};
+
+
+// расстояние между точками
+const double getDistance(const Point& one, const Point& two);
+
+Point operator+(const Point& one, const Point& two);
+
+Point operator*(const Point& p, double mult);
+
+Point operator/(const Point& p, double mult);
+
+double getDistancePointToSegment(const Point& p, const Segment& seg, double eps = 0.0000001);
+
+double getDistanceSegmentToSegment(const Segment& seg1, const Segment& seg2, double eps = 0.0000001);
+
+
+#endif //INC_3TERM_CONTESTS_GEOMETRY_H
diff --git a/mod3_a.cpp b/mod3_a.cpp
new file mode 100644
index 0000000..8899794
--- /dev/null
+++ b/mod3_a.cpp
@@ -0,0 +1,31 @@
+/*
+ * Даны два отрезка в пространстве (x1, y1, z1) - (x2, y2, z2) и (x3, y3, z3) - (x4, y4, z4).
+ * Найдите расстояние между отрезками.
+ *
+ * */
+
+
+#include <iostream>
+#include <math.h>
+#include <stdio.h>
+#include "geometry.h"
+
+
+int main() {
+    int x, y, z;
+
+    std::cin >> x >> y >> z;
+    Point a (x, y, z);
+    std::cin >> x >> y >> z;
+    Point b (x, y, z);
+    std::cin >> x >> y >> z;
+    Point c (x, y, z);
+    std::cin >> x >> y >> z;
+    Point d (x, y, z);
+
+    Segment seg1 (c, d);
+    Segment seg2 (a, b);
+
+    printf("%.9lf", getDistanceSegmentToSegment(seg1, seg2));
+    return 0;
+}
diff --git a/ternary_search.h b/ternary_search.h
new file mode 100644
index 0000000..965c2a6
--- /dev/null
+++ b/ternary_search.h
@@ -0,0 +1,20 @@
+#ifndef INC_3TERM_CONTESTS_TERNARY_SEARCH_H
+#define INC_3TERM_CONTESTS_TERNARY_SEARCH_H
+
+
+template <typename T, class Func>
+T ternarySearchMin(T left, T right, Func f, const double (*getDistance)(const T&, const T&), double eps = 0.0000001) {
+    while (getDistance(left, right) > eps) {
+        T a = (left * 2 + right) / 3;
+        T b = (left + right * 2) / 3;
+        if (f(a) < f(b)) {
+            right = b;
+        } else {
+            left = a;
+        }
+    }
+    return (left + right) / 2;
+}
+
+
+#endif //INC_3TERM_CONTESTS_TERNARY_SEARCH_H