#include <stdio.h>



char* s_unique(char* s) {
    char* p1, *p2;
    for(p1 = p2 = s; *p1; *p1 = *p2) {
        if(*p2 != *(p2 + 1))
            ++p1;
        ++p2;
    }
    return s;
}



int  main(void) {
  char s[] = "aaaaaaaaabcccdddddd";
  puts( s_unique(s) );
  return 0;
}

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