diff --git a/zeta_C/completed/26083.c b/zeta_C/completed/26083.c
new file mode 100644
index 0000000..9abaa7d
--- /dev/null
+++ b/zeta_C/completed/26083.c
@@ -0,0 +1,100 @@
+#include <stdio.h>
+
+typedef struct Date {
+    int year, month, day;
+} Date;
+
+Date *newDate(int year, int month, int day) {
+    if (0 <= year && year <= 99) {
+        if (1 <= month && month <= 12) {
+            if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12) {
+                if (1 <= day && day <= 31) {
+                    Date *date = (Date *) malloc(sizeof(Date));
+                    date->year = year;
+                    date->month = month;
+                    date->day = day;
+                    return date;
+                }
+            } else if (month == 2 && year % 4 == 0) {
+                if (1 <= day && day <= 29) {
+                    Date *date = (Date *) malloc(sizeof(Date));
+                    date->year = year;
+                    date->month = month;
+                    date->day = day;
+                    return date;
+                }
+            } else if (month == 2 && year % 4 != 0) {
+                if (1 <= day && day <= 28) {
+                    Date *date = (Date *) malloc(sizeof(Date));
+                    date->year = year;
+                    date->month = month;
+                    date->day = day;
+                    return date;
+                }
+            } else {
+                if (1 <= day && day <= 30) {
+                    Date *date = (Date *) malloc(sizeof(Date));
+                    date->year = year;
+                    date->month = month;
+                    date->day = day;
+                    return date;
+                }
+            }
+        }
+    }
+    return NULL;
+}
+
+void delDate(Date *date) {
+    free(date);
+    date = NULL;
+}
+
+int valid(Date *x, Date now) {
+    if (x == NULL) {
+        return 1;
+    }
+    if (x->year < now.year) {
+        return 0;
+    } else if(x->year > now.year) {
+        return 1;
+    }
+
+    if (x->month < now.month) {
+        return 0;
+    } else if (x->month > now.month) {
+        return 1;
+    } 
+
+    if(x->day < now.day) {
+        return 0;
+    } else if(x->day >= now.day) {
+        return 1;
+    }
+
+    return 0;
+}
+
+int main() {
+    int N;
+    Date NOW;
+    int first, second, third;
+    scanf("%d %d %d", &NOW.year, &NOW.month, &NOW.day);
+    scanf("%d", &N);
+    for (int i = 0; i < N; i++) {
+        scanf("%d %d %d", &first, &second, &third);
+        Date *d1 = newDate(first, second, third);
+        Date *d2 = newDate(third, second, first);
+        Date *d3 = newDate(third, first, second);
+        if (d1 == NULL && d2 == NULL && d3 == NULL) {
+            printf("invalid\n");
+        } else if (valid(d1, NOW) && valid(d2, NOW) && valid(d3, NOW)) {
+            printf("safe\n");
+        } else {
+            printf("unsafe\n");
+        }
+        delDate(d1);
+        delDate(d2);
+        delDate(d3);
+    }
+}
\ No newline at end of file