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diff --git a/challenge-102/paulo-custodio/cpp/ch-1.cpp b/challenge-102/paulo-custodio/cpp/ch-1.cpp
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+/*
+Challenge 102
+
+TASK #1 › Rare Numbers
+Submitted by: Mohammad S Anwar
+
+You are given a positive integer $N.
+
+Write a script to generate all Rare numbers of size $N if exists. Please
+checkout the page for more information about it.
+Examples
+
+(a) 2 digits: 65
+(b) 6 digits: 621770
+(c) 9 digits: 281089082
+*/
+
+#include <iostream>
+#include <cmath>
+
+int ipow(int base, int exp) {
+    int result = 1;
+    for (;;) {
+        if (exp & 1)
+            result *= base;
+        exp >>= 1;
+        if (!exp)
+            break;
+        base *= base;
+    }
+    return result;
+}
+
+int invert_number(int r) {
+    int r1 = 0;
+    while (r != 0) {
+        r1 = r1 * 10 + (r % 10);
+        r = r / 10;
+    }
+    return r1;
+}
+
+bool is_perfect_square(int n) {
+    double s = sqrt((double)n);
+    if (floor(s) == s)
+        return true;
+    else
+        return false;
+}
+
+void print_rare(int n) {
+    int start = ipow(10, n - 1);
+    int end = ipow(10, n );
+    for (int r = start; r < end; r++) {
+        int r1 = invert_number(r);
+        if (is_perfect_square(r + r1) && r >= r1 && is_perfect_square(r - r1))
+            std::cout << r << std::endl;
+    }
+}
+
+int main(int argc, char* argv[]) {
+    if (argc != 2) {
+        std::cerr << "Usage: ch-1 N" << std::endl;
+        return EXIT_FAILURE;
+    }
+    else
+        print_rare(atoi(argv[1]));
+}