diff --git a/zeta_C/1620.c b/zeta_C/1620.c
new file mode 100644
index 0000000..29063d2
--- /dev/null
+++ b/zeta_C/1620.c
@@ -0,0 +1,80 @@
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#define MAX_LENGTH 21
+
+typedef struct _Element {
+    int index;
+    char name[MAX_LENGTH];
+} Element;
+
+int ecomp(const void *a, const void *b) {
+    int c = strcmp((*(Element *) a).name, (*(Element *) b).name);
+    return c;
+}
+
+Element binsearch_idx(Element *dict, int N, int x) {
+    int start = 0;
+    int end = N - 1;
+    int mid;
+    while (start <= end) {
+        mid = (start + end) / 2;
+        if (dict[mid].index == x) {
+            break;
+        } else if (dict[mid].index > x) {
+            end = mid - 1;
+        } else {
+            start = mid + 1;
+        }
+    }
+    return dict[mid];
+}
+
+Element binsearch_str(Element *dict, int N, char *x) {
+    int start = 0;
+    int end = N - 1;
+    int mid;
+    while (start <= end) {
+        mid = (start + end) / 2;
+        int c = strcmp(dict[mid].name, x);
+        if (c == 0) {
+            break;
+        } else if (c > 0) {
+            end = mid - 1;
+        } else {
+            start = mid + 1;
+        }
+    }
+    return dict[mid];
+}
+
+int main() {
+    int N, M;
+    scanf("%d %d", &N, &M);
+    Element *dictionary = (Element *) calloc(N, sizeof(Element));
+    Element *str_dictionary = (Element *) calloc(N, sizeof(Element));
+    for (int i = 0; i < N; i++) {
+        scanf("%s", dictionary[i].name);
+        dictionary[i].index = i + 1;
+    }
+
+    memmove(str_dictionary, dictionary, sizeof(Element) * N);
+
+    qsort(str_dictionary, N, sizeof(Element), ecomp);
+
+    for (int i = 0; i < M; i++) {
+        char temp[MAX_LENGTH];
+        scanf("%s", temp);
+        Element e;
+        if (temp[0] <= '9' && temp[0] >= '0') {
+            e = binsearch_idx(dictionary, N, atoi(temp));
+            printf("%s\n", e.name);
+        } else {
+            e = binsearch_str(str_dictionary, N, temp);
+            printf("%d\n", e.index);
+        }
+    }
+
+    return 0;
+}
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