diff --git a/a3/program.c b/a3/program.c
index c35de32..4f930fe 100644
--- a/a3/program.c
+++ b/a3/program.c
@@ -36,7 +36,7 @@ int main() {
         for (int j = i + 1; j < count; j++) {
             int k = 0;
             while (names[i][k] && names[i][k] == names[j][k]) k++;
-            if (names[i][k] - names[j][k] > 0) {
+            if ((unsigned char)names[i][k] > (unsigned char)names[j][k]) {
                 int t = 0;
                 while ((tmp[t] = names[i][t])) t++;
                 t = 0;
@@ -50,7 +50,7 @@ int main() {
     for (int i = 1; i < count; i++) {
         int k = 0;
         while (names[i][k] && names[i][k] == names[unique - 1][k]) k++;
-        if (names[i][k] != names[unique - 1][k]) {
+        if ((unsigned char)names[i][k] != (unsigned char)names[unique - 1][k]) {
             int t = 0;
             while ((names[unique][t] = names[i][t])) t++;
             unique++;