sgu 302

#include <stdio.h>
#include <string.h>

void putUpper(char c) {
    if (c >= 'a') {     //c is lowercase
        putchar(c - 32);
    }
    else {
        putchar(c);
    }
}

void putLower(char c) {
    if (c <= 'Z') {      // c is Uppercase
        putchar(c + 32);
    }
    else {
        putchar(c);
    }
}

int main() {
    char s[1009];
    char f[1009];
    int k = 0;          // f and k as stack, the last one is the nearest tag
    int i = 0;

    s[0] = '\0';
    scanf("%s", s);

    while (s[i] != '\0') {
        if (s[i] == '<') {      // si is a tag
            ++i;
            if (s[i] == '/'){       //si is the right tag, pop stack
                --k;
            }
            else {                  //si is the left tag, push stack
                ++k;
                f[k] = s[i];
            }
            while (s[i] != '>') ++i;     //i went to the end of tags
        }
        else {
            if (k == 0) {               //si is not betwwen tag
                putchar(s[i]);
            }
            else if (f[k] == 'D') {     //si si between DOWN tag
                putLower(s[i]);
            }
            else {                      //si is between UP tag
                putUpper(s[i]);
            }
        }
        ++i;
    }

    return 0;
}