=IFERROR(
    ADDRESS(
        MIN(IF((B2:AD100="example") * (OFFSET(B2:AD100; -1; 0) <> "OK"); ROW(B2:AD100); 1048576));
        MIN(IF((B2:AD100="example") * (OFFSET(B2:AD100; -1; 0) <> "OK") * (ROW(B2:AD100) = MIN(IF((B2:AD100="example") * (OFFSET(B2:AD100; -1; 0) <> "OK"); ROW(B2:AD100); 1048576))); COLUMN(B2:AD100); 1048576));
        4
    );
    "Not found"
)