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

//------------------------------------------------------------------
static int x2i(int i){
    i = toupper(i);
    i = i - `0`;
    if(i > 9){
        i = i - `A` + `9` + 1;
    }
    return i;
}

//------------------------------------------------------------------
static int urldecode(char* s){
    int c, c1, n;
    char *s0,*t;

    t = s0 = s;
    n = strlen(s);
    while(n > 0){
        c = *s++;
        if(c == `%` && n > 2){
            c = *s++;
            c1 = c;
            c = *s++;
            c = 16 * x2i(c1) + x2i(c);
            n -= 2;
        }
        *t++ = c;
        n--;
    }
    *t = 0;
    return t - s0;
}

//------------------------------------------------------------------
int main(int argc, char *argv[]){
    char line[128] = "%ED%95%9C%EA%B8%80";

    urldecode(line);
    puts(line);

    return 0;
}