int isNumber(char *str) {
    int i = 0;
    if (str[0] == '-' || str[0] == '+') i = 1;
    if (str[i] == '\0') return 0;
    for (; str[i] != '\0'; i++) {
        if (!isdigit(str[i])) return 0;
    }
    return 1;
}

int main() {
    int n, i, oldVal, newVal, found = 0;
    char buffer[5000];

    if (!fgets(buffer, sizeof(buffer), stdin)) {
        printf("Invalid input\n");
        return 0;
    }
    buffer[strcspn(buffer, "\n")] = 0;
    if (!isNumber(buffer)) {
        printf("Invalid input\n");
        return 0;
    }
    n = atoi(buffer);
    if (n < 0 || n > 1000) {
        printf("Invalid input\n");
        return 0;
    }

    if (!fgets(buffer, sizeof(buffer), stdin)) {
        printf("Invalid input\n");
        return 0;
    }
    buffer[strcspn(buffer, "\n")] = 0;

    int arr[1000];
    char *token = strtok(buffer, " ");
    int count = 0;

    while (token != NULL) {
        if (!isNumber(token)) {
            printf("Invalid input\n");
            return 0;
        }
        if (count >= n) {
            printf("Invalid input\n");
            return 0;
        }
        arr[count++] = atoi(token);
        token = strtok(NULL, " ");
    }
    if (count != n) {
        printf("Invalid input\n");
        return 0;
    }

    if (!fgets(buffer, sizeof(buffer), stdin)) {
        printf("Invalid input\n");
        return 0;
    }
    buffer[strcspn(buffer, "\n")] = 0;

    char *oldValStr = strtok(buffer, " ");
    char *newValStr = strtok(NULL, " ");
    if (oldValStr == NULL || newValStr == NULL || strtok(NULL, " ") != NULL) {
        printf("Invalid input\n");
        return 0;
    }
    if (!isNumber(oldValStr) || !isNumber(newValStr)) {
        printf("Invalid input\n");
        return 0;
    }
    oldVal = atoi(oldValStr);
    newVal = atoi(newValStr);

    for (i = 0; i < n; i++) {
        if (arr[i] == oldVal) {
            arr[i] = newVal;
            found = 1;
        }
    }

    if (!found) {
        printf("Value not found\n");
        return 0;
    }

    for (i = 0; i < n; i++) {
        printf("%d", arr[i]);
        if (i < n - 1) printf(" ");
    }
    printf("\n");

    return 0;
}