int getchar();
int putchar(int ch);
int printf(char* format, ...); 

int main() {
    int ch;
    while ((ch = getchar()) != -1) {
        if (ch == '\\') {
            ch = getchar();
            if (ch == 'n') {
                ch = '\n';
            } else if (ch == 't') {
                ch = '\t';
            } else if (ch == 'r') {
                ch = '\r';
            } else if (ch == '0') {
                ch = '\0';
            } else if (ch == '\\') {
                ch = '\\';
            } else if (ch == '\'') {
                ch = '\'';
            } else if (ch == '\"') {
                ch = '\"';
            } else {
                printf("unexpected escaped character: '\\%c'\n", ch);
                return 1;
            }
        }
        putchar(ch);
    }
    return 0;
}